Sleep Deprivation: Understanding The Science Behind Fatigue

Sleep is an essential part of our lives, and not getting enough of it can have a detrimental impact on our health and well-being. Sleep deprivation can manifest in various ways, such as fatigue, low energy, poor balance and coordination, mood changes, mental health issues, forgetfulness, and a weakened immune system. It can also lead to more severe health issues like heart disease, obesity, and type 2 diabetes.

While the recommended amount of sleep varies with age, most adults require 7-9 hours of sleep per night for optimal health. Not getting enough sleep can be due to various factors, including stress, nutrient deficiencies, underlying health conditions, caffeine consumption, inadequate hydration, obesity, and shift work, among others.

Chronic insomnia, a common sleep disorder, is characterised by the inability to fall asleep or maintain restorative sleep, leading to daytime fatigue and impaired functioning. It is a significant concern, affecting about 10% of the world's population and disrupting various aspects of daily life.

Understanding the causes of tiredness when we don't sleep is crucial for taking appropriate measures to improve our sleep quality and overall health.

Circadian rhythm and its impact on sleep

Circadian rhythms are 24-hour cycles that are part of the body's internal clock, which runs in the background to carry out essential functions and processes. The circadian rhythm uses light, dark, and our biological clock to regulate body temperature, metabolism, hormones (including melatonin), and sleep.

The master clock is called the suprachiasmatic nucleus (SCN) and is located in a region of the brain. The SCN controls melatonin production, which helps regulate sleep. During the day when it's light outside, melatonin levels remain low. Later in the day, as it grows darker, our bodies produce more melatonin, with levels peaking between 2 and 4 a.m. before falling again. Our bodies are best primed to fall asleep about two hours after melatonin levels start to rise.

The circadian rhythm is responsible for daily fluctuations in wakefulness, body temperature, metabolism, digestion, and hunger. It also controls memory consolidation (the formation of long-term memories occurs during sleep) and the timing of hormone secretion.

A person's circadian tendency can affect their choice of emotional coping skills and their predisposition to psychological disorders. An irregular circadian rhythm can negatively affect a person's ability to sleep and function properly, leading to various health problems, including mood disorders such as depression, anxiety, bipolar disorder, and seasonal affective disorder.

Shift work, travel across time zones, social or study habits, illness, stress, frequent sleep disruptions, or a noisy and bright sleep environment can all disrupt the circadian rhythm. Misalignment between your circadian rhythms and your environment can have serious consequences for your health and well-being, including sleep problems, performance issues, emotional and social difficulties, accidents, and various health problems.

To maintain a healthy circadian rhythm, it is important to keep a consistent routine and sleep schedule, avoid naps late in the day, exercise during the daytime, and avoid screens and bright light before bed.

Sleep disorders

Sleep is a complex biological process that is critical to both physical and mental health. When we don't get enough quality sleep, it can affect our physical and mental health, thinking, and daily functioning.

There are over 80 different types of sleep disorders, with insomnia being the most common. Sleep disorders involve problems with the quality, timing, and amount of sleep, which result in daytime distress and impairment in functioning.

Insomnia

Insomnia is a sleep disorder characterised by difficulties falling or staying asleep. It can be acute (short-term) or chronic (long-term), with the latter known as insomnia disorder. Insomnia can be primary, meaning it occurs on its own, or secondary, indicating it is a symptom of another condition. About one-third of adults experience insomnia symptoms, and 4-22% meet the criteria for insomnia disorder.

Sleep Apnea

Sleep apnea is a breathing disorder characterised by interruptions in breathing during sleep, lasting 10 seconds or more. This can cause repeated episodes of airway obstruction, resulting in snoring, snorting, gasping, or breathing pauses. Sleep apnea can lead to daytime sleepiness and fatigue. It is typically diagnosed through a clinical sleep study.

Restless Leg Syndrome (RLS)

RLS involves a tingling or prickly sensation in the legs, along with a powerful urge to move them. It is often accompanied by uncomfortable and unpleasant sensations that can be relieved by moving or massaging the legs. RLS can disrupt sleep, leading to daytime sleepiness. It typically affects individuals in their teens or twenties, with a prevalence of up to 3% in the population.

Circadian Rhythm Disorders

These disorders involve problems with the sleep-wake cycle, making it difficult to fall asleep and wake up at the right times. They can be caused by internal factors, such as a person's body clock being different from the light-dark cycle, or external factors like shift work or jet lag. Circadian rhythm disorders can lead to significant sleep problems and extreme sleepiness during the day.

Parasomnia

Parasomnia refers to unusual behaviours during sleep, such as walking, talking, or eating. It includes various disorders such as sleepwalking, sleep terrors, nightmare disorder, and rapid eye movement (REM) sleep behaviour disorder. These disorders can cause significant distress and impair daily functioning.

Hypersomnia

Hypersomnia is characterised by excessive daytime sleepiness, even when individuals get at least seven hours of sleep. It includes conditions like narcolepsy, where people experience an irrepressible need to sleep multiple times a day. Hypersomnia can lead to difficulty concentrating, memory issues, and problems with daily functioning.

Other Factors Contributing to Sleep Problems

In addition to sleep disorders, there are other factors that can contribute to sleep problems:

• Caffeine and alcohol consumption
• Irregular sleep schedules, such as working night shifts
• Ageing: Older adults often experience less sleep and spend less time in the deep, restful stage of sleep.

The impact of diet and nutrition on sleep

Diet and nutrition have a significant impact on sleep quality. A well-balanced diet containing adequate amounts of carbohydrates, fat, and protein is ideal for good sleep. Consuming too much or too little protein can negatively affect sleep.

Foods that help you sleep

• Cherries
• Oily and fatty fish (herring, mackerel, salmon, tuna, sardines, trout, and krill)
• A diet high in vegetables
• Grain mixes containing tryptophan

Consuming simple carbohydrates that quickly turn into sugar in the bloodstream about four hours before bedtime can help people fall asleep faster. However, this may not be a good long-term strategy, as high-sugar and high-carbohydrate diets are associated with poor sleep quality.

Foods that can disrupt sleep

• Caffeine
• Alcohol
• High-fat foods, especially saturated fat
• Foods low in tryptophan
• Diets high in carbohydrates and low in fat

Other factors to consider

• Skipping meals and snacking between meals or late at night can reduce sleep quality and quantity.
• Eating too much food or too close to bedtime may also interfere with healthy sleep.
• Consuming caffeine within 4-6 hours of bedtime can negatively impact sleep quality.
• Exposure to blue light from electronic devices can disrupt sleep by suppressing melatonin production.

Sleep and mental health

Mood Disorders

Chronic insomnia and sleep deprivation can lead to mood disorders such as depression and anxiety. Research shows that people with insomnia are twice as likely to experience depression, and about 80% of people with depression experience insomnia. Sleep deprivation can cause fatigue, low energy, and excessive sleepiness, which can then lead to moodiness and agitation.

Stress

Chronic stress can lead to fatigue and, in some cases, stress-related exhaustion disorder (ED). It can also cause structural and functional changes in the brain and lead to chronic inflammation, which contributes to symptoms like fatigue. Managing stress through therapy or other means can help improve sleep quality.

Cognitive Function

Sleep deprivation can affect cognitive function, including memory, attention, and concentration. Deep stages of sleep are responsible for learning and memory, and a lack of sleep can disrupt these processes. Additionally, sleep helps clear toxins from the brain, and a lack of sleep has been linked to an increased risk of Alzheimer's disease and other forms of dementia.

Behaviour

Sleep deprivation can lead to changes in behaviour, such as irritability, moodiness, and increased errors or accidents. It can also affect social interactions and personal relationships, as people may become too tired to socialise or engage in activities they usually enjoy.

Overall Mental Health

Sleep deprivation can negatively impact overall mental health, making it harder to manage and process emotions. People with sleep deprivation are more likely to experience symptoms of depression and anxiety. It is important to address sleep issues and practice good sleep hygiene to support mental health and well-being.

Sleep deprivation and its health risks

Sleep deprivation is a condition where a person doesn't get enough sleep or fails to get good quality sleep. This can be a short-term issue, lasting one or a few nights, or it can be a chronic concern persisting for weeks, months, or even years. Sleep deprivation can have various causes, from shift work and alcohol use to sleep apnea and mental health issues. While it is usually treatable, it can have several negative consequences and increase the risk of specific health conditions if left unaddressed.

Health Risks of Sleep Deprivation

Heart and Circulatory Systems

Chronic sleep deprivation can have long-term detrimental effects on cardiovascular health. Those affected are more likely to develop high blood pressure (hypertension) and high cholesterol (hyperlipidemia). It can also lead to hypertension heart disease, resulting from long-term unmanaged high blood pressure.

Metabolic Systems

People with long-term sleep deprivation are at a significantly higher risk of developing Type 2 diabetes. Sleep deprivation disrupts key hormone levels, including ghrelin, leptin, and cortisol, which can contribute to weight gain and obesity.

Immune System

Sleep is crucial for the body's immune system to function properly. A lack of sleep impairs the body's ability to produce cytokines, proteins that are essential for maintaining immune system function. As a result, the body starts producing more white blood cells, creating an imbalance that weakens the immune system over time. Consequently, individuals experiencing sleep deprivation become more susceptible to illnesses and take longer to recover.

Nervous System

Sleep-deprived individuals often experience higher pain sensitivity, making them feel pain more easily and intensely.

Brain

While the exact role of sleep in brain function is not fully understood, sleep deprivation has been found to negatively impact brain function. It hinders learning and memory and may play a role in the development of Alzheimer's disease. Research also suggests that sleep is necessary for the brain to clear out toxins, and a lack of sleep can lead to a buildup of toxins associated with neurodegenerative diseases.

Mental Health

Sleep deprivation can make it harder for individuals to manage and process their emotions, increasing the likelihood of experiencing symptoms of depression and anxiety. It can also contribute to or exacerbate mental health issues, creating a cycle that reinforces itself.

Frequently asked questions