This article examines the scientific literature, demonstrating the detrimental effects of poor sleep hygiene on various cognitive functions, including attention, memory, executive functions, and emotional regulation, which significantly impact decision-making processes.

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Sleep hygiene, encompassing a set of behaviours and environmental factors that promote healthy sleep, plays a crucial role in cognitive performance and decision-making. Specifically, we explore how inadequate sleep stemming from poor sleep hygiene can lead to impaired judgment, increased risk-taking behaviour, and reduced ability to assess risks and rewards. Furthermore, we discuss the underlying neurobiological mechanisms through which sleep influences cognitive function and decision-making.

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Sleep Hygiene

Sleep, an essential physiological process, is fundamental for maintaining physical and mental health [1]. A significant portion of the population experiences insufficient or poor-quality sleep, often attributed to inadequate sleep hygiene [2]. Sleep hygiene refers to a collection of practices and environmental factors designed to promote consistent and restful sleep.

Poor sleep hygiene encompasses behaviours such as irregular sleep schedules, excessive screen time before bed, consumption of caffeine or alcohol close to bedtime, and an unsuitable sleep environment [3]. The consequences of poor sleep hygiene extend beyond daytime fatigue; they profoundly impact cognitive function, significantly affecting performance and decision-making capabilities [4].

Decision-making, a complex cognitive process involving the evaluation of options and the selection of the optimal course of action, is crucial in various aspects of life, from everyday choices to high-stakes professional scenarios [5]. The ability to make sound judgments, accurately assess risks, and regulate emotions is paramount for effective decision-making [6]. However, sleep deprivation and disrupted sleep patterns, often resulting from poor sleep hygiene, impair these key cognitive functions, ultimately compromising the quality of decisions made [7].

By synthesising current scientific findings, this paper will emphasise the importance of prioritising sleep as a critical factor for enhancing performance and promoting effective decision-making.

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Impact of Poor Sleep Hygiene on Cognitive Performance

The detrimental effects of sleep deprivation, often stemming from poor sleep hygiene, on cognitive performance have been extensively documented [8]. It is critical to understanding the cognitive domains that are most sensitive to sleep disruption. These include:

1. Attention and Alertness: Sleep deprivation significantly impairs attention and alertness. Studies have shown that individuals with inadequate sleep exhibit reduced sustained attention, making them more prone to errors and lapses in concentration [9]. Sustained attention is vital for tasks requiring continuous monitoring and vigilance, such as driving or operating machinery. Poor sleep hygiene can lead to chronic sleepiness, making it difficult to maintain focus and react quickly to unexpected events [10].
2. Memory and Learning: Sleep plays a crucial role in memory consolidation, the process by which newly acquired information is stabilised and integrated into long-term memory stores [11]. Sleep deprivation disrupts this process, impairing both working memory and long-term memory formation [12]. Working memory, responsible for temporarily holding and manipulating information, is essential for problem-solving and decision-making. Studies have demonstrated that poor sleep hygiene can lead to reduced working memory capacity and impaired ability to encode new information [13].
3. Executive Functions: Executive functions encompass a set of higher-order cognitive processes, including planning, problem-solving, and cognitive flexibility. These functions are essential for goal-directed behaviour and adaptive responses to changing circumstances [14]. Sleep deprivation impairs executive functions, leading to reduced cognitive flexibility, difficulty in shifting between tasks, and impaired planning abilities [15]. Individuals with poor sleep hygiene may struggle with complex tasks that require careful planning and execution.
4. Emotional Regulation: Sleep deprivation can significantly impact emotional regulation, increasing irritability, anxiety, and susceptibility to negative emotions [16]. Poor sleep hygiene can disrupt the delicate balance of neurotransmitters involved in emotional processing, leading to heightened emotional reactivity and difficulty in controlling impulses [17]. This can manifest as increased sensitivity to stress and reduced ability to cope with challenging situations.

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The Link Between Sleep Hygiene and Decision-Making

The cognitive impairments resulting from poor sleep hygiene directly impact decision-making processes. Several studies have demonstrated that sleep deprivation can lead to:

1. Impaired Judgment and Reasoning: Adequate sleep is essential for sound judgment and logical reasoning. Sleep deprivation can impair the ability to assess information accurately, identify potential consequences, and make rational decisions [18]. Individuals suffering from sleep deprivation may rely on heuristics or mental shortcuts, leading to biased and suboptimal decisions.
2. Increased Risk-Taking Behaviour: Sleep deprivation has been linked to increased risk-taking behaviour. Studies have shown that individuals with inadequate sleep are more likely to engage in risky behaviours, such as gambling or reckless driving [19]. This may be due, in part, to the impaired prefrontal cortex function, which plays a critical role in risk assessment and impulse control. Reduced sleep can diminish the ability to evaluate potential risks and rewards accurately, resulting in poor decision-making.
3. Reduced Accuracy in Risk and Reward Assessment: Sleep is crucial for accurately assessing risks and rewards. Sleep deprivation can impair the brain's ability to process information related to potential gains and losses, leading to miscalculations and poor choices [20]. This is crucial in financial decision-making, where accurate risk assessment is essential for maximising returns and minimising losses.
4. Ethical Decision-Making: Even ethical considerations can be affected. Studies have shown that reduced sleep leads to less ethical decision-making regarding moral choices. [21]

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Neurobiological Mechanisms Underlying the Effects of Sleep on Cognition and Decision-Making

The impact of sleep on cognitive function and decision-making is mediated by several neurobiological mechanisms. Understanding these mechanisms is crucial for developing targeted interventions to improve sleep and enhance cognitive performance:

1. Prefrontal Cortex Function: The prefrontal cortex (PFC) is a brain region critically involved in executive functions, decision-making, and emotional regulation [22]. Sleep deprivation impairs PFC function, leading to reduced cognitive control, impaired planning abilities, and increased impulsivity [23]. The PFC is particularly sensitive to the effects of sleep loss, and its dysfunction can significantly compromise decision-making abilities.
2. Hippocampus and Memory Consolidation: The hippocampus, a brain structure crucial for memory formation, is also vulnerable to the effects of sleep deprivation [24]. Sleep plays a vital role in transferring information from the hippocampus to the neocortex for long-term storage. Sleep deprivation disrupts this process, impairing memory consolidation and reducing the availability of information for decision-making [25].
3. Neurotransmitter Systems: Sleep deprivation alters the balance of neurotransmitter systems, including dopamine, norepinephrine, and serotonin, which play crucial roles in regulating mood, attention, and motivation [26]. Changes in these neurotransmitter levels can affect cognitive performance and decision-making by influencing attention span, cognitive flexibility and impulse control [27].
4. Glymphatic System: Recent research highlights the role of the glymphatic system, a brain-wide waste clearance system, which is most active during sleep [28]. Sleep deprivation reduces glymphatic function, leading to the accumulation of metabolic waste products in the brain. This accumulation can impair neuronal function and contribute to cognitive decline [29].
5. Amygdala & Emotion: The amygdala, responsible for processing emotions, becomes more active and reactive when sleep-deprived. This hyperactive amygdala, combined with a less functional PFC (responsible for regulating the amygdala) leads to impaired emotional decision-making.

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Strategies for Improving Sleep Hygiene

Given the significant impact of sleep on cognitive performance and decision-making, improving sleep hygiene is crucial for optimising cognitive function and enhancing overall well-being. Evidence-based strategies for improving sleep hygiene include:

1. Establishing a Regular Sleep Schedule: Maintaining a consistent sleep-wake cycle, even on weekends, helps regulate the body's natural circadian rhythm, promoting better sleep quality [30]. Consistent bedtimes and wake-up times can improve sleep efficiency and reduce sleep latency (the time it takes to fall asleep).
2. Creating a Relaxing Bedtime Routine: Engaging in relaxing activities before bed, such as reading, taking a warm bath, or listening to calming music, can help prepare the body and mind for sleep [31]. Avoid stimulating activities, such as watching television or using electronic devices, close to bedtime.
3. Optimising the Sleep Environment: Creating a sleep-conducive environment is essential for good sleep quality. The bedroom should be dark, quiet, and cool [32]. Use blackout curtains, earplugs, or a white noise machine to minimise distractions. Maintaining a comfortable temperature in the bedroom can also promote restful sleep.
4. Avoiding Caffeine and Alcohol Before Bed: Caffeine and alcohol can interfere with sleep patterns [33]. Caffeine, a stimulant, can disrupt sleep onset and reduce sleep depth. Alcohol, while initially inducing drowsiness, can disrupt sleep architecture and lead to fragmented sleep during the later part of the night.
5. Regular Exercise: Regular physical activity can improve sleep quality. However, it is important to avoid strenuous exercise close to bedtime [34]. Exercise can increase body temperature and alertness, making it difficult to fall asleep.
6. Limiting Screen Time Before Bed: The blue light emitted from electronic devices can suppress melatonin production, a hormone that regulates sleep [35]. Avoiding screen time for at least an hour before bed can improve sleep quality. Using blue light filters or apps that reduce blue light emissions can also be helpful.
7. Cognitive Behavioural Therapy for Insomnia (CBT-I): For individuals struggling with chronic insomnia, CBT-I is an evidence-based treatment that addresses the underlying psychological and behavioural factors that contribute to sleep problems. CBT-I involves techniques such as sleep restriction, stimulus control, and cognitive restructuring.

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The Importance of Prioritising Sleep

1. In a society that often glorifies long working hours and sacrifices sleep for productivity, prioritising sleep hygiene is essential for optimising performance and enhancing decision-making.
2. Recognising the crucial role of sleep in cognitive function and overall well-being is the first step toward fostering a culture that values and promotes healthy sleep habits.
3. Educational campaigns and workplace initiatives can raise awareness about the importance of sleep hygiene and provide individuals with the knowledge and resources to improve their sleep habits.
4. Organisations can support their employees' sleep health by implementing policies that encourage flexible work schedules, promote adequate breaks, and discourage excessive screen time during evenings.
5. Implementing sleep monitoring programs and providing access to sleep specialists can further help employees identify and address sleep problems.

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Limitations and Future Research

While the evidence supporting the role of sleep hygiene in cognitive performance and decision-making is substantial, there are limitations to be acknowledged. Many studies rely on subjective measures of sleep quality, which may be influenced by recall bias.

Future research should incorporate more objective measures of sleep, such as polysomnography and actigraphy, to provide a more accurate assessment of sleep patterns. Additionally, more research is needed to investigate the long-term effects of poor sleep hygiene on cognitive function and decision-making. Longitudinal studies that track individuals' sleep habits and cognitive performance over time can provide valuable insights into the cumulative impact of sleep deprivation.

Further, research should focus on identifying individual differences in susceptibility to sleep deprivation and developing personalised interventions to improve sleep hygiene. Tailoring sleep hygiene interventions to address specific needs and preferences can enhance adherence and improve outcomes. Furthermore, investigating the impact of specific sleep hygiene interventions (e.g., blue light reduction, specific exercise types) on targeted cognitive domains could lead to more refined and effective strategies.

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Take-home Message

1. Sleep hygiene plays a critical role in cognitive performance and decision-making.
2. Poor sleep hygiene leads to sleep deprivation and disrupts various cognitive functions, including attention, memory, executive functions, and emotional regulation.
3. These cognitive impairments negatively impact decision-making, leading to impaired judgment, increased risk-taking behaviour, and reduced accuracy in assessing risks and rewards.
4. The underlying neurobiological mechanisms that mediate the effects of sleep on cognition and decision-making involve the prefrontal cortex, hippocampus, neurotransmitter systems, and the glymphatic system.
5. Improving sleep hygiene through evidence-based strategies, such as establishing a regular sleep schedule, creating a relaxing bedtime routine, optimising the sleep environment, and avoiding caffeine and alcohol before bed, is crucial for optimising cognitive function and enhancing decision-making.
6. Prioritising sleep as a critical factor for overall well-being is essential for fostering a culture that values and promotes good sleep habits.

Disclaimer: The views and opinions expressed in this article are those of the author and do not necessarily reflect the official policy or position of M3 India.

About the author of this article: Dr Partha Ghosh, BNYS, MD(YS), is a general physician and a medical writer from Siliguri, Darjeeling.