Shift Work: The Cognitive and Physiological Risks Faced by Healthcare Workers
- Renaldo Pool, BHSc
- 4 days ago
- 29 min read
Effects of circadian disruption and sleep deprivation on cognitive function, intervention strategies, and future research for improving healthcare personnel's health.
Introduction
Shift work is an essential part of any organization’s continuous operation. Even though it is often unknown to the public, especially diagnostic and patient care services that are required around the clock, many laboratory personnel face the reality of shift work daily. Alternating and extended shift schedules ensure the continuity of healthcare services, prioritizing patient care at all times; however, for healthcare personnel, it comes at a hidden cost.
As a medical laboratory scientist involved in daily laboratory operations, I am accustomed to working alternating shifts. My idea of regular working hours differs from the "normal" hours typically seen in other careers. In addition to personal experience, scientific evidence highlights the impact of disruptive shift patterns on cognitive function, mental well-being, and physical health. It extends far beyond feelings of fatigue, where the circadian rhythm becomes disrupted, emotional regulation is altered, and memory function is affected, leading to long-term changes in brain structure.
Given the essential role that laboratory personnel play in the healthcare industry, it is valuable to highlight how the extension of shift hours and persistent alternating shift patterns impact their day-to-day work and lives. Managing stress-induced situations, which require rapid decision-making, sharp focus, and attention to detail, not only affects personal health but can also negatively impact laboratory workflow, safety, diagnostic expertise, and ultimately, patient outcomes. Thus, this article highlights the effects of irregular shift patterns on neurocognitive and physiological well-being, while also suggesting intervention options for both employers and laboratory personnel.
Key Concepts
Shift work, specifically night and alternating shift schedules, has a significant impact on regular sleep-wake cycles and circadian rhythms, resulting in prompt and lasting cognitive alterations, especially with continuous shift work patterns.
Shift workers are prone to an increased risk of cognitive decline, even when working only a few days or nights of extended shifts. A drop in attention, vigilance, working memory, and executive function is noticeable. In turn, it increases exposure to errors and accidents, especially in laboratory environments.
When exposure to shift work and night shifts is long-term, accompanied by long hours and irregular schedules, changes occur in the cognitive structure – the brain undergoes volume changes in areas associated with memory, attention, and emotional regulation, which increases brain aging.
The effect of shift work on neurohormonal regulation is profound, particularly in terms of cortisol and melatonin release, which impacts the circadian rhythm. Moreover, gene expression involved in the circadian cycle is also altered, affecting stress regulation, immune function, as well as other metabolic functions.
Employers and policymakers must address the effects of shift work on their employees’ cognitive health by introducing interventions to mitigate or minimize long-term cognitive impairments induced by prolonged shift hours and irregular shift schedules.
Short-Term Effects of Shift Work
The Impact of Extended Shift Hours on Cognitive Performance
Scientific evidence on this topic has revealed the neurocognitive decline that healthcare workers undergo during and after long shifts, especially with three consecutive 12-hour shifts (Chellapa et al., 2019). It was noted that individuals’ attention span and predicted effectiveness related to cognition deteriorate immensely (Chellapa et al., 2019). This is usually accompanied by feelings of exhaustion or tiredness, based on their personal experience and input provided. The adverse effect on neurocognition is notable after more than 10 hours of work, alongside circadian disruption exacerbating cognitive decline in individuals working shifts for a prolonged period (Caruso, 2014; Chellapa et al., 2019; Vlasak et al., 2021).
One such study, which included bedside nurses, found that significant changes occurred at the beginning and end of a 12-hour shift (Miller, 2020). Sixty-six percent of nurses had lower Montreal Cognitive Assessment (MoCA) scores during night shifts compared to day shifts (Miller, 2020). The two groups were compared based on the main areas of cognitive impairment: attention, processing speed, working memory, visual attention span, and psychomotor vigilance (Miller, 2020).
Altered Sleep Quality and Sleep Deprivation’s Effects on Cognition
The exposure of healthcare personnel to alternating shift schedules, including night shift work, is accompanied by disrupted sleep patterns or reduced sleep hours. In turn, its effects are pronounced in the consequences it has for cognitive functionality. These individuals face greater challenges regarding their sleep quality due to disrupted sleep patterns, which is also linked to circadian rhythm disruption (Ahmad et al., 2020; Vlasak et al., 2021). When these cycles, which are interconnected, become dysregulated, it affects emotional regulation, cognitive task processing speed, physical task efficiency, and working memory (Park et al., 2020; Yao et al., 2025c). If an individual’s sleep quality is disrupted, their performance at work becomes impaired, accompanied by feelings of fatigue. Research indicates that 32% of individuals report disruptions to their sleep-wake cycle, resulting in inadequate sleep (Caruso, 2014). This further enhances cognitive decline due to disruptive sleep patterns becoming chronic. It also imposes additional risks to healthcare workers at their place of work, such as increased chances of injuries and ineffective decision-making capabilities (Caruso, 2014; Vlasak et al., 2021; Ren et al., 2025).
Long-term Impact of Shift Work: Brain Structure Changes Disrupt Optimal Functionality
Grey Matter and the Glymphatic System
Recently, a study revealed that healthcare workers exposed to more than 52 hours of work a week showed significant changes in brain structure affecting executive function and emotional regulation (Jang et al., 2025c). These findings indicated that an increased grey matter volume in study participants working more than 52 hours a week is a significant finding, albeit with a positive or negative impact. Typically, a greater volume of grey matter indicates the benefits of the learning and practice processes; however, in this case, it could highlight the adverse effects of overworked individuals. Similarly, elevated grey matter volume and cortical thickness have been reported in individuals with varying depressive states (Jang et al., 2025c). Contrastingly, a study by Ye et al. (2023) indicated a decrease in the posterior grey matter volume of the brain, which correlated with elevated levels of Ab-levels after one night of shift work, referred to as sleep deprivation. Ab- and Tau-protein levels are typically removed by the glymphatic system during sleep; however, the findings highlight the impact of the reduced amount of sleep on the glymphatic system, which usually regulates waste clearance during sleep (Ye et al., 2023). Due to extended periods of wakefulness, a build-up of these proteins is noted, leading to an increased amyloid presence in the brain. Elevated levels of these proteins have been associated with different neurodegenerative conditions in previous research (Ye et al., 2023).
Increased Volume in Different Brain Regions
Moreover, functional magnetic resonance imaging (fMRI) scans indicated a 19% elevation in brain volume, specifically in the left caudal middle frontal gyrus, with additional changes seen in 17 different regions in the brain, such as the insula and superior temporal gyrus, to name a few (Jang et al., 2025c). The affected areas participate in cognitive, attentional, memory, and emotional processing functions (Dong et al., 2024b; Jang et al., 2025c). These findings from research suggest that prolonged working hours lead to neuroadaptive alterations, potentially affecting the cognition and emotional well-being of individuals over a period (Dong et al., 2024b).
Cerebellum Size Alteration and Hippocampal Volume Changes
Using various neuroimaging techniques in research has indicated structural changes in the brain, which are observed in individuals who work shifts, such as laboratory workers and healthcare personnel (Choi et al., 2025). One such study utilized voxel-based morphometry (VBM, a computational image analysis of specific brain regions obtained through magnetic resonance imaging), showing a significant reduction in the size of cerebellar areas compared to non-shift workers, while simultaneously affecting the inferior parietal gyrus by increasing its volume (Choi et al., 2025). Although this study was one of the few that analyzed MRI data using VBM, it is not without its limitations, including the omission of lifestyle factors and other potential confounding factors. Thus, it could translate to occupational-acquired effects, alongside shift work patterns, which alter the brain’s neuroplasticity (Choi et al., 2025). A major alteration to consider is the cerebellum’s involvement, given the vital function of this area of the brain, not only for healthcare workers but also for the general public. This is the part of the brain responsible for motor control, coordination, and cognitive processing – critical functions when it comes to laboratory techniques that require precision and accuracy (Choi et al., 2025). The larger inferior parietal gyrus may be an adaptive response to compensate for the reduced cerebellum size and the continuous cognitive demands; however, the loss of neuroplasticity is a significant cost to pay (Choi et al., 2025).
Hippocampal volume reduction is also directly linked to poor sleep quality and slower psychomotor speed. Years of prolonged exposure to shift work have been correlated with greater decreases in hippocampal size (Song et al., 2024; Yook et al., 2024b).
Shift Work Affects White Matter Structure
With diffusion tensor imaging (DTI), research has shown that current shift workers have deteriorated white matter integrity when compared to previous shift workers and a control group. The findings indicated 15 affected connectivity matrices (evident as a decreased number of fibers present) (Ning et al., 2022). The deterioration was established by measuring a marker of cerebral small vessel disease, peak-width skeletonized mean diffusivity (PSMD), which indicates current and ongoing neurological damage, particularly during active shift work. The role of white matter is also essential for laboratory personnel and other healthcare professionals, as it is responsible for fast information processing, executive function, and remaining attentive while focusing on a specific task (Ning et al., 2022; Dong et al., 2024b). Also considered essential for laboratory functions. Moreover, the research conducted indicates that shift work induces a chronic inflammatory state, leading to the progressive injury of the brain’s communicative networks.
Persistent Cognitive Deficits in Shift Workers Compared to Non-Shift Workers
An accumulation of cognitive defects occurs when healthcare workers continuously endure shift work; the effect extends beyond experiencing fatigue. This is highlighted in a meta-analysis, which indicates that shift workers experience worse work performance compared to non-shift workers, particularly in terms of their work speed, working memory, awareness of physical movement, cognitive control, and visual attention (Vlasak et al., 2021; Song et al., 2024). Furthermore, healthcare personnel have a higher odds ratio (4.45 times) of experiencing poor cognitive function and decreased resilience compared to individuals in administrative positions (Amer et al., 2024); however, no significance was found between deteriorating cognitive health and low resilience in healthcare workers (Amer et al., 2024). It can be deduced that the cognitive deficit is linked to the period of exposure to shift work, which correlates with increased cognitive deterioration.
Poor Sleep Quality Linked to Accelerated Brain Aging
A 2024 study using electroencephalogram (EEG) sleep data showed higher brain age markers in night shift workers (Yook et al., 2024b). This was correlated with the duration of working night shift and the increase in brain aging, specifically having a profound negative impact on older shift workers. The acceleration in brain aging was also linked to poor deep sleep (N3) patterns, further suggesting the effect of shift work on the restorative processes occurring in the brain during sleep (Yook et al., 2024b). More specifically, for laboratory staff, a progressive deterioration of cognitive function is observed over the years of shift work experience, with these alterations persisting even during recovery periods (Yao et al., 2025c). It could highlight permanent changes to the brain structure and function. Research shows that healthcare professionals who have more than 10 years of shift work experience have cognitive deterioration that is equal to 6.5 years of age-related decline.
Disruptions in Neurotransmitters, Circadian Rhythms, and Genetic Expression
The Impact of Shift Work and Sleep Deprivation on the GABA System
Lower gamma-aminobutyric acid (GABA) levels have been correlated with improper sleep patterns, which is especially the case in healthcare personnel who work alternating shifts and night shifts (Park et al., 2020; Cirrincione et al., 2023). GABA functions by regulating sleep processes, inhibiting the activation of neuronal cells during the sleep period that are involved in wakefulness stimulation (Park et al., 2020; Cirrincione et al., 2023). Moreover, GABA also controls rapid eye movement (REM) and non-REM sleep cycles, including deep wave sleep, which is essential for restorative cognitive processes. Reduced GABAergic activity in the occipital cortex, anterior cingulate cortex, and medial prefrontal cortex was found in individuals with sleep disorders, such as insomnia, which was also found to affect their working memory functionality (Park et al., 2020). Therefore, the concern regarding lower GABA levels is based on the consequences it has for the standard inhibitory control on neuronal excitability, upholding attention, and mitigating cognitive errors (Cirrincione et al., 2023).
Serotonin Dysregulation
Throughout studies conducted, a consistent finding noted is reduced serotonin levels in alternating shift workers. The impact of serotonin dysregulation is crucial, as it plays an integral part in the circadian cycle as well as mood stabilization. For instance, a study comparing 437-day shift workers with 246 rotating shift workers found that the day shift workers had much higher levels than alternating shift workers, which also highlighted a significant difference between the two groups (Sookoian et al., 2007). Furthermore, a study conducted by Shehata et al. (2021) found that nursing staff working different shift patterns exhibited abnormal serotonin levels, which also predicted poor sleep quality (Cirrincione et al., 2023). Alternating shift workers and permanent night shift nurses had the highest prevalence of lower serotonin levels, 66.7% and 65%, respectively (Shehata et al., 2021).
Prolonged Work Hours’ Impact on Dopamine and More
A study focusing on emergency physicians revealed that dopamine levels were lower during a 24-hour shift period and did not recover to baseline after a few rest days (Dutheil et al., 2024). It would only return to normal after three days of working 24-hour shifts. Norepinephrine was seen to be elevated twofold during night shift as well, indicative of an active chronic state of the stress response mechanism (Vivarelli et al., 2023; Dutheil et al., 2024). Moreover, epinephrine excretion rates were also significantly elevated between being off duty and on duty; the highest change in excretion rates was noted during nighttime. This further shows that shift work activates the sympatho-adrenomedullary system, with different patterns of response between these two neurostimulants (Boettcher et al., 2020). Based on the findings of this study, it can be inferred that laboratory personnel may also be negatively affected by prolonged high stress hormone levels and a decrease in dopamine. This, in turn, affects motivation, emotional regulation, attention, and executive function (Dutheil et al., 2024; Andreadi et al., 2025).
In addition, cortisol is another neural hormone that is upregulated during shift work, also partly induced by physical or mental stress. Cortisol’s normal function includes the vital role it plays during stress response; however, due to the circadian clock dysregulation and altered cortisol secretion, it implicates shift workers’ mental health through interference with the HPA axis (Vivarelli et al., 2023; Andreadi et al., 2025).
Genetic Changes and Their Role in Circadian Disruption
Cognitive defects resulting from long-term exposure to night shift work are primarily attributed to the constant disruption of the circadian system (Ahmad et al., 2020). With night shift work, changes in gene expression occur, where 302 genes are identified as being upregulated and 78 as being downregulated after one night shift. Studies have also revealed that these altered gene expression patterns correlate with conditions such as major depressive disorder (Nukiwa et al., 2025b).
Moreover, when the circadian rhythm is disrupted, it causes the misalignment of internal systems, such as clock genes staying on a day-oriented schedule characterized by lowered amplitudes, and metabolites shifting by several hours (Vlasak et al., 2021; Nukiwa et al., 2025b). For instance, research revealed that expressed genes, such as CLOCK, NPAS2, PER1, PER3, and REV-ERBα, were elevated in alternating night shift workers, with lower expression of the BMAL1 and CRY1 genes, compared to day workers (Boivin et al., 2021; Nukiwa et al., 2025b). The changes in gene expression are associated with metabolic dysfunction, where several genes are upregulated, which correlates with postprandial triglycerides and markers of insulin resistance.
More recently, a novel brain mechanism of post-translational modifications (PTMs) was described by Zheng et al. (2025b). It involves monoamine neurotransmitters, such as serotonin, dopamine, and histamine, which are typically responsible for regulating various brain functions and behaviors (Zheng et al., 2025b). It does this by binding monoamines to histones, which modifies them and regulates brain circadian gene expression processes, neural plasticity, as well as wake-sleep cycles (Resuehr et al., 2019; Ye et al., 2022; Zheng et al., 2025b). It can be inferred that the disruption of this mechanism in shift workers, alongside changes in gene expression, is a contributing factor to neurological dysfunction.
Additionally, changes in gene expression activate the innate immune system, which is accompanied by inflammatory responses (Nukiwa et al., 2025b). A previous study has reported findings where inflammatory markers, such as interleukin-6 (IL-6), become increased after one night of sleep deprivation (Ye et al., 2023).
Hypothalamic-Pituitary-Adrenal (HPA) Axis
The body’s stress response system is regulated by the HPA axis but is severely disrupted during shift work (Brum et al., 2022). This is based on the disruption of the circadian clock system, which causes alterations in the alignment of the circadian system in response to the light-dark cycle (Resuehr et al., 2019). An internal desynchronization between different levels of the circadian system also characterizes it (Resuehr et al., 2019; Boivin et al., 2021; Brum et al., 2022).
How Does Circadian Disruption Impact Cortisol’s Function?
The physiological role of cortisol, produced by the adrenal glands, is to act as the primary stress hormone, the final product of the HPA axis, which is responsible for governing stress management, metabolism, immune response, and other physiological processes (Brum et al., 2022; Andreadi et al., 2025). It regulates the physiological response to stress through energy mobilization, inflammation control, and improving cognitive processes during acute stress stimuli. Alongside the sympathetic nervous system, it regulates the release of glucose from the liver to provide rapid energy during periods of stress (Andreadi et al., 2025).
Cortisol also plays an integral part in the internal synchronicity between central and peripheral circadian clocks (Boivin et al., 2021). Typically, cortisol levels are at their highest in the mornings (07:00 – 08:00 AM) and at their lowest around 02:00 – 04:00 AM (Brum et al., 2022). The suprachiasmatic nucleus (SCN) in the hypothalamus is the main regulator of this circadian rhythm (Ahmad et al., 2020; Boivin et al., 2021; Vlasak et al., 2021; Brum et al., 2022). Moreover, cortisol’s role in cognitive function is essential through its activity with the mineralocorticoid and glucocorticoid receptors. Where the prefrontal cortex expresses GR for executive functioning, the hippocampus expresses both receptors, playing a crucial role in memory formation (De Alcubierre et al., 2023).
It is well known that cortisol is characterized by an inverted U-shaped curve, where a moderate cortisol concentration aids in memory formation and consolidation; however, extremely low or high levels negatively influence cognition (Andreadi et al., 2025). Cortisol awakening response (CAR) is the key factor responsible for regulating the spatiotemporal mechanisms of larger brain networks responsible for emotional and executive functions (Brum et al., 2022). Research has focused on the disruption of cortisol, specifically in night shift nurses, where they have a lower cortisol awakening response (CAR) compared to day-shift nurses. The night shift nurses were showing very low levels 30 minutes after waking, compared to their day shift counterparts (Brum et al., 2022; Andreadi et al., 2025). In the case of laboratory personnel working alternating shifts, their cortisol curves are changed or blunted, showing lower amplitudes and less pronounced peaks and troughs (Boivin et al., 2021; Andreadi et al., 2025). Night staff personnel require a minimum of four days for their circadian rhythms of cortisol release to adjust, as noted, and it has also been observed that cortisol profiles do not completely return to normal (Andreadi et al., 2025).
One such study revealed that salivary cortisol exhibits a normal circadian rhythm, which is consistent in both day and night shift workers. However, a lowered threshold was observed in night-shift workers during both their working hours and days off, indicating that the body attempts to regulate cortisol levels even when circadian disruption occurs (Brum et al., 2022; Andreadi et al., 2025).
Moreover, altered circadian rhythm affects synaptic proteins; for instance, a study focusing on circadian regulation through light exposure showed excitatory synapse density at its highest during the day (or in the case of active state during the night, which was referred to as subjective day) being inversely proportional to locomotor activity (Jasinska et al., 2024). During the night shift, with continuous light exposure, cyclic alterations in synaptic density are observed, accompanied by persistent high levels. This relates to the disruption of light-dark cycles, which affects the circadian rhythm, and has a direct impact on synaptic plasticity (Jasinka et al., 2024).
Disrupting Melatonin Production
With night shift work, melatonin production is suppressed due to light exposure during working hours, a process that occurs quite rapidly (Boivin et al., 2021; Brum et al., 2022). When melatonin is suppressed, it poses a problem for regulating the circadian rhythm, which in turn affects insulin production, function, and ultimately, glucose homeostasis (Yao et al., 2025c).
The Impact of Shift Work on Work Efficiency
When healthcare workers, especially laboratory personnel, experience long-term exposure to different shift patterns, neurocognitive defects progress and become pronounced. In certain instances, these alterations have profound lasting implications when they bypass temporary cognitive performance.
Changes in Cognitive Domains
Different cognitive areas of the brain are implicated due to the causal factor of shift work patterns. A meta-analysis of 18 studies, which included 18 802 workers, revealed that shift workers had poorer performance in comparison with non-shift workers, in the following areas: processing speed, working memory, psychomotor vigilance, spatial orientation, cognitive control, and visual attention (Vlasak et al., 2022; Yao et al., 2025c). Cognitive control was one of the most significant areas affected, especially for laboratory staff, which suggests that altered cognitive function and control thereof can have severe consequences if safety protocols and accurate task execution are not adhered to (Vlasak et al., 2022; Yao et al., 2025c).
Rise in Work Errors
Cognitive deterioration due to long work hours is associated with an increase in medical errors, with fatigue being a significant contributing factor to mistakes made (Fathizadeh et al., 2024). For instance, a comprehensive review noted that 82% of errors occur due to fatigue, and with one unit of self-reported fatigue increase, a 25% elevation in medication administration errors and near misses is made (Bell et al., 2023). In addition, when residents work extended hours, sometimes exceeding 24 hours, 36% of serious mistakes made in intensive care units are attributed to overexertion and sleep deprivation (Ren et al., 2025). This vicious cycle of expected overtime work leads to an increased risk of needlestick injuries, work-related illnesses, and a higher incidence of absenteeism (Caruso, 2014; Holmelid et al., 2024).
Altered Attention Span and Affected Vigilance
Research conducted on medical laboratory technologists indicated that these individuals experience attention deficits when exposed to night shift work (Yao et al., 2025c). This impacts the clinical accuracy of laboratory operations and patient-centered diagnostics. Factors such as fatigue, sleep quality, and drowsiness can predict a reduction in alertness, especially when working a night shift (McHill & Wright, 2019). Furthermore, instances of laboratory errors during the night shift led to a disruptive workflow and the repetition of laboratory tests, ultimately impacting turnaround time and resource utilization.
This serves as an example of the real-world implications of shift work’s influence on cognitive health. In addition, laboratory-based research using the Psychomotor Vigilance Task (PVT) has highlighted the slower median reaction times of laboratory personnel working night shifts, with elevated attention lapses and difficulty maintaining a high level of vigilance (McHill & Wright, 2019; Vlasak et al., 2021; Van Egmond et al., 2022). The impact on laboratory workflow is significant, as vigilance is essential in the laboratory setting for monitoring instrument function and malfunction, as well as hands-on analysis of complex analytical procedures.
Furthermore, longitudinal studies emphasize the implication of consecutive night shift work leading to cognitive deterioration. Laboratory staff included in these studies have shown reduced accuracy, slower reaction times, and an increased tendency to make errors (McHill & Wright, 2019; Song et al., 2024). It emphasizes the long-term effects of extended shift work and alternating shift schedules, which progressively affect cognition and lead to poor laboratory practice.
Disruption of Large-Scale Brain Networks
The Default Mode and Attention Networks
Additional studies have shown, through neuroimaging techniques, that shift workers experience changes in their large-scale brain networks. Specifically, an increase in functional connectivity across seven different brain networks was discovered; however, a reduction in functional connectivity was observed between brain networks involved in visual-frontoparietal, visual-default mode, and attention networks (Yao et al., 2025c; Wu et al., 2025). Alterations in these brain networks directly impact cognitive performance, where scores of immediate memory, visuospatial, and delayed memory processing were linked with disrupted functional connectivity (Dong et al., 2024b; Wu et al., 2025). Furthermore, changes in the auditory cortex, thalamus, visual cortex, and somatosensory functions were also seen, specifically in a study pertaining to 24-hour sleep-deprived nurses, using fMRI (functional magnetic resonance imaging).
Structure-Function Coupling Abnormalities
A decrease in structure-function connections in essential brain areas is also matched with shift work disorder (Wu et al., 2025). These include the left anterior cingulate gyrus, central opercular cortex, middle frontal gyrus, and parietal operculum cortex. These areas are involved in attention networks, and thus, when disrupted, also affect the functioning of the attention networks (Dong et al., 2024b; Yao et al., 2025c; Wu et al., 2025).
The Influence of Disrupted Sleep Patterns on Cognitive Recovery
Disrupted Deep Sleep Patterns
Research also discusses the effect of shift work on sleep patterns and sleep structure, revealing a decrease in the activity of delta and sigma wave frequencies associated with non-rapid eye movement sleep (Yook et al., 2024b). This phase of deep sleep is crucial for memory consolidation, toxin removal from the brain, and cognitive restoration. Night shift workers, who experience consistent poor sleep quality, have a higher percentage of N1 sleep, reduced N3 sleep percentage, and a larger arousal index (in other words, they are more prone to wake from external stimuli, as they do not transition to the deep sleep cycle) (Park et al., 2020; Cirrincione et al., 2023; Yook et al., 2024b). This was also correlated with an elevation in brain aging, highlighting the effects of shift work and disrupted sleep patterns that prevent the brain from undergoing restorative processes (Yook et al., 2024b).
Sleep Deprivation and Cognitive Recovery
One would think that it would be easy to adjust to changes in shift schedules; however, there is currently limited evidence that cognitive adaptation occurs following consecutive night shifts (Boivin et al., 2021). A field-based study found that night shift workers are unlikely to exhibit a change or ability to adapt in their cortisol and melatonin rhythms after exposure to three consecutive night shifts (Boivin et al., 2021). Using simulated night-shift protocols, research has indicated a continuous disruptive pattern in cognitive performance, particularly concerning psychomotor alertness, clarity of thought, and executive function (Ren et al., 2025). Furthermore, this suggests that despite changes in shift work patterns, especially with rotating shifts, the disrupted cognitive aftermath remains, showing no or minimal notable recovery. This, however, is subject to individual chronotype and other factors, warranting further investigation into this area of sleep disruption and cognitive recovery.
Early Biomarker Identification for Neural Decline
Measuring Biomarkers for Early Indication of Neural Decline
The detection of biomarkers specific to central nervous system (CNS) injury was highlighted by recent research in shift workers. Van Egmond et al. (2022) highlight the elevation of neurofilament light chain levels through their findings, which is an indication of axonal damage, particularly for women exposed to night shifts. In addition, shift workers experienced an increase in pTau181 concentration, which is associated with tau protein pathology typically found in neurodegenerative conditions such as Alzheimer’s Disease (Van Egmond et al., 2022). It further highlights the negative consequences of shift work through both detectable and measurable CNS biomarker tests. It would benefit laboratory personnel working alternating shifts to monitor these biomarkers for the early detection of neurocognitive dysregulation, prior to the onset of clinical symptoms.
Measures Implemented for Stress Response Biomarker Detection
By using new approaches to detect biomarkers associated with neural and bodily stress responses, measuring urinary catecholamines, such as urinary sulfatoxymelatonin, provides an effective method (Boivin et al., 2021). It is considered non-invasive, offering the convenience of sample collection, and is able to detect stress responses during night shifts (Vivarelli et al., 2023). It can be used as an immediate or acute detection method, or over a prolonged period. As such, dopamine concentration is considered a biomarker that is significantly altered due to long-term changes in the circadian rhythm. Furthermore, measuring the salivary levels of cortisol, alpha-amylase, and melatonin posits a method that correlates with neurobehavioral changes (Vivarelli et al., 2023). A study conducted indicated that a positive relationship exists between morning salivary cortisol and a depression scale, and a negative correlation between morning salivary alpha-amylase levels and the ability to work scale (Vivarelli et al., 2023).
Additional Physiological Effects
In addition to the neurobiological implications associated with long-term shift work, further physiological changes should be considered, which are far more concerning than feelings of fatigue.
With the combined effects of neurotransmitter disruption, hormonal dysregulation, and alterations in synaptic activity, an increase in catecholamine levels and a significant physiological impact led to an elevated risk of cardiovascular disease (Vlasak et al., 2022).
Shift work is considered a contributor to epidemiological risk, alongside other environmental and lifestyle factors, which can lead to an increased risk of cardiovascular conditions, sleep disorders, diabetes mellitus, and obesity (Vlasak et al., 2022). |
Meta-analytical studies indicated that shift workers have an average of 40% chance of elevated ischemic heart disease risk, in comparison with regular day workers (Caruso, 2014). Moreover, a combination of occupational stress, stress-related disruptive sleep-wake cycle, and circadian dysregulation, alongside an altered automatic cardiac control, elevates the risk of cardiovascular disease (Andreadi et al., 2025). Recommendations based on the researchers’ findings highlight that exposure to 24-hour shifts should be limited to decrease or prevent these risks, regardless of the healthcare position held by the individual.
A prolonged period of shift work causes an increase in total white blood cell count, with neutrophils, lymphocytes, and monocytes showing elevated levels. Additionally, C-reactive Protein (CRP) and Interleukin-6 (IL-6) are also increased, suggesting disruption to the immune system (Ye et al., 2023; Nukiwa et al., 2025b). The HPA axis is affected by chronic stress and inflammatory response exposure, elevating cortisol levels and leading to tissue-resident increases of glucocorticoid signals.
Additionally, the International Agency for Research on Cancer has indicated that shift work is “probably carcinogenic to humans,” especially when it disrupts the biological circadian rhythmicity (Costa, 2010). Due to the circadian cycle disruption taking place during shift work, cellular function becomes affected, altering DNA repair, cell cycles, and cell death. In certain circumstances, it could increase an individual’s risk for cancer development due to continuous molecular disruptions. Furthermore, studies have also shown that shift work exposure increases the mortality risk of an individual, with a higher risk of developing breast cancer and stroke, as well as an increased risk associated with death from all causes and cardiovascular disease (Costa, 2010; Caruso, 2014; Nukiwa et al., 2025b).
Future Focus and Potential Intervention Strategies to Prevent the Impact of Shift Work
With recent evidence indicating the implications of shift work, night shift schedules, disrupted sleeping patterns, and cognitive overload from highly demanding precision tasks in the laboratory environment, mitigating strategies should be seriously considered.
Healthcare authorities and occupational health systems should consider the impact of contributing factors to neurocognitive degeneration in healthcare workers, especially laboratory personnel, and recognize that it progresses beyond mere fatigue. The long-term effect on neurological function and changes in brain structure should be addressed through interventions.
Intervention Strategies
Preventative measures can be taken to limit sudden shift changes, allowing for adequate rest between consecutive shifts. Ergonomic, evidence-based shift scheduling should be considered, taking individual chronotypes into account to promote the resilience of shift workers.
Reducing the number of consecutive night shifts and extending shifts provides a guideline where longer shift hours are infrequent and regular break intervals during shifts are allowed to mitigate fatigue accumulation.
The work environment could implement optimized workplace lighting through blue-enriched light during the night shift period, and decrease the amount of natural light exposure prior to daytime sleep (e.g., using blackout curtains and blue light-blocking glasses) to maintain the circadian rhythm.
Providing comprehensive educational workshops related to proper sleep hygiene and stress tolerance management in the workplace provides a supportive environment for employees. Topics that can be included in these sessions should cover maintaining consistent sleep routines, reducing caffeine intake late in the day, minimizing screen time, and promoting resilience-building strategies through peer and family support.
Short naps or resting periods should be encouraged, especially during extended or night shift coverage, for temporary restoration of cognitive function. Careful planning of rest periods should be essential to minimize work disruptions.
Adapting occupational policies to include routine cognitive and physical health monitoring, through standardized screening techniques, could help detect early risks of cognitive or physical deterioration.
Implementing real-time monitoring of cognition, physical, and metabolic activity through digital tools provides an additional measure of risk detection, especially in cases where cognitive overload or fatigue can occur. These steps ensure that shift handovers or small breaks are taken to provide short-term relief.
Future Areas for Further Research
Investigating the effects of evidence-based, ergonomic shift scheduling with minimal disruption to the circadian system, on the real-time monitoring of cognitive abilities and overall physiological health for determining early identification of cognitive impairment.
Providing insight through longitudinal studies relating to persistent cognitive deterioration with prolonged exposure to shift work and circadian disruption, accompanied by the cognitive recovery potential of shift work cessation.
Correlating advanced brain imaging techniques and biomarker analysis for a holistic overview of cognitive decline affecting different brain regions.
Assess prevention strategies incorporated with personalized genetic and chronotype assessments to determine whether cognitive impairment is reduced. Prevention strategies, such as light therapy, dietary changes, and physical exercise, designed on an individual level, should also be taken into account.
Extensive cohort studies with diverse demographics should be conducted to determine the impact of shift work, circadian dysregulation, and sleep deprivation on the metabolic, cardiovascular, immune, and mental health of participants.
Leveraging AI tools for research-focused predictive model integration with real-time physiological, cognitive, and workplace performance could aid in identifying high-risk workers, enabling a comprehensive risk analysis approach to mitigate errors and improve employee well-being.
Conclusion
Although shift work is considered an essential part of various industries’ continuous 24-hour, 7-day-a-week operations, especially in healthcare, the effects and risks associated with cognitive function and physiological health have been substantiated through numerous research studies.
Alterations to metabolic secretory patterns, neural hormones, and gene expression have negative consequences for healthcare workers who are already exposed to stress-induced and high-pressure work environments, requiring attentiveness and precision. It not only affects the long-term health of individuals but also poses a danger to the safety of laboratory personnel and patient care outcomes. Suppose sleep deprivation, altered circadian patterns, and metabolic changes persist. In that case, the adverse effects of cognitive dysregulation and brain structure changes will have long-term consequences that might not be fully recoverable.
Employers and policymakers are in a position to provide immediate guidance and implement structural changes within companies that promote the health and safety of their personnel. Identifying and preventing exposure to unhealthy working conditions not only benefits the long-term relationship with the employee through prevention strategies, recovery, and resilience initiatives but also provides an environment where the quality of patient care can continue to be prioritized. Through various intervention approaches, continuous monitoring of employee neural function and mental health ensures that the 24-hour healthcare system remains functional and delivers the highest quality patient care.
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