A Comprehensive Guide: Sleep for Health, Performance, and Longevity
Executive Summary
A good night’s sleep (approximately 7–9 hours per night for adults) is essential for optimal brain and body function, and is not a luxury but a basic biological need. In fact, there is not a single physiological process in the body that is not improved by sleep, or impaired by sleep deprivation.
Here are some practical recommendations for immediately improving sleep quality:
A regular sleep routine and time: Maintain consistent sleep and wake times every day, even on weekends. A stable routine strengthens the body’s clock and makes it easier to fall asleep and wake up. Plan enough time to get at least 7 hours of sleep at night.
An ideal sleep environment: Create a dark, quiet, and cool room. A room temperature of around 18°C is considered optimal for sleep. In addition, using technologies such as mattresses and cooling surfaces has been shown to improve sleep quality, especially for people who tend to overheat at night.
Limit blue light and screens in the evening: Avoid screens for about two hours before bed, or use blue light filters.
Caffeine and alcohol: Avoid caffeine starting in the early afternoon, and limit alcohol consumption in the evening, especially on flights. Alcohol and caffeine are dehydrating and impair sleep quality.
Bedtime relaxation routine: Adopt a calming ritual, such as a hot shower, reading, or meditation. And avoid arousing activities like going over emails and working.
Regular daily exercise: Exercise regularly, but avoid strenuous activity close to bedtime.
Using your bed only for sleep: Strengthen the brain connection between bed and sleep by avoiding other activities in bed.
Supplements and medications (in a graduated approach): After behavioral changes have been exhausted, scientifically recommended supplements (such as melatonin and magnesium) can be considered for moderate support. In more complex cases, prescription medication is an option. Modern medications with a low risk of dependence are available, such as trazodone (at low doses) or orexin blockers such as Dayvigo. They should be used for a short period of time and under medical supervision. In any case, for chronic insomnia, cognitive-behavioral therapy (CBT-I) is the first and most effective line of treatment.
Addressing specific challenges: In conditions such as jet lag, focus should be placed on rapid synchronization with the local clock through scheduled light exposure and planned use of melatonin. In menopausal women, sleep disorders caused by hormonal changes (such as hot flashes) require a targeted approach, including hormone replacement therapy (HRT) or behavioral therapies (CBT-I) as effective solutions.
Implementing these recommendations is expected to significantly improve sleep quality, daytime alertness, and work performance.
Scientific Background: The Importance of Sleep for Health and Cognitive Function
Comprehensive scientific studies show that adequate sleep is a cornerstone of physical and mental health. In contrast, chronic sleep deprivation or fragmented sleep harms almost all body systems.
Physical Health
Sleeping less than the recommended amount (less than 7 hours per night) is statistically associated with a higher risk of developing obesity, type 2 diabetes, hypertension, and cardiovascular disease (5,25). Large reviews have found that the relationship between sleep duration and health is U-shaped—sleeping too little (less than 6 hours) or too much (more than 9–10 hours) is associated with an increased risk of chronic disease and mortality, compared with the optimal 7–8 hours of sleep (5).
Chronic sleep deprivation disrupts hormonal and metabolic balance: it increases levels of stress hormones (such as cortisol and adrenaline) and appetite, disrupts insulin activity, and lowers levels of leptin (a satiety hormone) – a combination that contributes to increased hunger and weight gain (27). This has long-term consequences such as an increased risk of metabolic syndrome. In addition, poor sleep weakens the immune system: for example, a study found that people who slept less than 5–6 hours a night were significantly more likely to catch a cold after exposure to a virus, compared to those who slept 7 hours or more (25).
Cognitive function and mental performance
From a neurological perspective, the brain needs sleep to recover and process information. During deep sleep (NREM stage), humans consolidate and store memories of the day’s events, and during the dream stage (REM) stage, important processes of learning and emotional regulation take place (24). Even partial sleep deprivation leads to significant impairments in attention, concentration, reaction time, and learning ability.
In fact, studies have shown that every hour of sleep lost causes a consistent decline in cognitive function. A recent 2023 review of studies noted that there is almost no cognitive domain that is not affected by sleep deprivation (16): prolonged wakefulness causes a slowdown in thinking, impaired working memory, decreased creativity and inference, and impaired judgment and decision-making (16). Brain imaging (fMRI) has shown that after a night without sleep, there is a decrease of up to 40% in the ability of the hippocampus (the brain’s memory center) to encode new memories compared to a night with normal sleep (28).
Sleep deprivation causes the brain to work less coordinated: for example, the activity of the amygdala (the emotional center) increases by about 60% during sleep deprivation due to decreased inhibitory connections from the prefrontal cortex (28). The result is emotional hyperreactivity—fatigue causes sadness, irritability, and increased stress. A classic experiment dramatically illustrated the cognitive impairments: a group of subjects deprived of sleep for 24 consecutive hours showed impaired functioning equivalent to a person with a blood alcohol concentration of 0.1% (double the legal driving limit in some states), and even 17–19 hours without sleep were enough to achieve impairment equivalent to a blood alcohol concentration of 0.05% (30).
Emotional stability
During fatigue, the neural activity that regulates the prefrontal cortex to the emotional centers decreases, so that the amygdala operates “over-freely.” Therefore, sleep deprivation leads to increased emotional reactivity – irritability, a tendency to get angry or cry, and increased feelings of stress.
Long-term brain health
Sleep is also essential for maintaining brain function over the years. During sleep, especially during the deep stages of sleep, essential “brain maintenance” occurs: the removal of waste and metabolic byproducts from brain cells (for example, the clearance of amyloid-β, a protein whose accumulation is associated with Alzheimer’s disease (32)). Insufficient sleep has been linked in epidemiological studies to