Daytime Sleep: Why Do We Need So Much?

Sleep is an essential part of our lives, but sometimes we can find ourselves sleeping too much. Oversleeping is defined as sleeping for more than the recommended number of hours and can be a symptom of an underlying health condition. The amount of sleep we need varies from person to person, but on average, healthy adults are recommended to get 7 to 9 hours of sleep per night. If you're regularly sleeping more than this and still feel tired, it could be a sign of a sleep disorder or another health issue.

Sleep disorders, such as insomnia, hypersomnia, and sleep apnea

Sleep disorders such as insomnia, hypersomnia, and sleep apnea can all cause excessive sleepiness and make you sleep all day.

Insomnia

Insomnia is a common sleep disorder, affecting around 10% of the world's population. It involves disruptions in sleep patterns, making it difficult to fall or stay asleep. This can lead to sleep deprivation, causing daytime sleepiness and impairing your ability to function properly. Insomnia can be acute (short-term) or chronic (long-term), and can be caused by various factors such as stress, life changes, medical conditions, mental health issues, or sleep hygiene.

Hypersomnia

Hypersomnia is characterised by extreme daytime sleepiness despite getting adequate or more than adequate nighttime sleep. People with hypersomnia may experience recurrent episodes of sleep during the day and have difficulty staying awake, impacting their work, social life, and overall quality of life. The exact causes of hypersomnia are often unknown, but it may be related to neurotransmitters, genetics, or other underlying medical or mental health conditions.

Sleep Apnea

Sleep apnea is a condition where the upper airway collapses during sleep, causing interruptions in breathing. This results in fragmented sleep and excessive sleepiness during the day. Obstructive sleep apnea is caused by a blockage in the airway, while central sleep apnea occurs when the brain fails to send signals to the muscles controlling breathing. Sleep apnea can lead to a higher risk of accidents, heart rate irregularities, and decreased oxygen levels.

Underlying health conditions, including mental health disorders, neurological issues, and infections

Sleep is closely connected to mental and emotional health and has demonstrated links to several mental health disorders, including depression, anxiety, bipolar disorder, and others. Research shows that the relationship between sleep and mental health is bidirectional, meaning that sleeping problems may be both a cause and a consequence of mental health problems. For example, while insomnia was historically viewed as a symptom of depression, evidence now suggests that poor sleep may also induce or exacerbate depression.

In addition to mental health disorders, neurological issues can also impact sleep. Obstructive sleep apnea (OSA), for example, is a sleep disorder that involves pauses in breathing during sleep and a reduction in the body's oxygen levels, leading to fragmented and disturbed sleep. OSA occurs more frequently in people with psychiatric conditions and may contribute to physical health issues and severe mental distress.

Infections can also impact sleep. Respiratory infections, in particular, have been found to affect sleep, with individuals spending more time in bed and sleeping longer, but also experiencing more disturbed sleep. This may be due to the body's immune response to infection, as well as the impact of symptoms such as fever, cough, and congestion.

It is important to note that underlying health conditions can interact with and influence each other. For instance, mental health disorders can increase the risk of certain infections, and infections can worsen mental health symptoms. Therefore, addressing and managing these conditions is crucial for improving overall health and well-being, including sleep quality.

Medication and substance use, including antidepressants, stimulants, and alcohol

Medication and substance use can significantly impact sleep. This includes the use of antidepressants, stimulants, and alcohol.

Antidepressants

Some antidepressants can cause sleep problems, including prescription drugs such as selective serotonin reuptake inhibitors (SSRIs) and tricyclic antidepressants, as well as nonprescription drugs like pseudoephedrine (Sudafed). These substances can interfere with the process of falling asleep and maintaining sleep, and alter sleep cycles, resulting in reduced sleep quality and increased daytime sleepiness.

Stimulants

Stimulant use can lead to sleep disturbances, with individuals experiencing sleepiness, fatigue, or difficulty functioning during the day. This includes the use of illegal stimulants like cocaine, amphetamines, and methamphetamines, as well as prescription stimulants for conditions like attention deficit hyperactivity disorder (ADHD). The disruptive effects of stimulants on sleep can impact next-day functioning and increase the risk of accidents.

Alcohol

Alcohol is often considered a sedative, and while it can induce sleep, it also disrupts sleep quality. Alcohol increases wakefulness during the second half of the night as its effects wear off, preventing individuals from getting deep sleep and rapid eye movement (REM) sleep. This can result in daytime fatigue and sleepiness. Additionally, alcohol relaxes the muscles, including those in the throat, which can lead to breathing difficulties and further sleep disruptions. Older adults are particularly vulnerable to alcohol-related sleep disorders due to higher blood alcohol levels compared to younger adults.

Lifestyle factors, such as poor sleep habits, physical inactivity, and electronic device use before bed

Poor Sleep Habits

Inadequate or insufficient sleep is one of the most common causes of excessive sleepiness. This can be due to various factors, such as long working hours, shift work, family demands, or social life. Maintaining a consistent sleep schedule and practising good sleep hygiene are crucial for optimal sleep. This includes sticking to a regular sleep and wake-up time, even on weekends, creating a relaxing bedtime routine, and ensuring the bedroom environment is comfortable and conducive to sleep.

Physical Inactivity

Regular physical activity and exercise play a vital role in promoting good sleep. Engaging in physical activity during the day can improve sleep quality and help regulate sleep patterns. Incorporating exercise into your daily routine can make it easier to fall asleep at night and improve overall sleep quality. However, it is important to avoid strenuous exercise too close to bedtime, as it may have the opposite effect and make it harder to wind down.

Electronic Device Use Before Bed

The use of electronic devices, such as smartphones, tablets, and computers, before bedtime can disrupt sleep. These devices emit blue light, which suppresses the production of melatonin, the hormone that makes us feel sleepy. As a result, using these devices before bed can increase alertness when we should be preparing for sleep. Additionally, the content consumed on these devices, such as social media or stimulating games, can also contribute to sleep disturbances. It is recommended to limit screen time before bed and opt for relaxing activities that do not involve electronic devices to improve sleep quality.

In summary, addressing these lifestyle factors can play a crucial role in improving sleep quality and reducing feelings of sleepiness during the day. Establishing healthy sleep habits, engaging in regular physical activity, and minimising electronic device use before bed are key steps towards achieving more restful sleep.

Genetic factors, with some people naturally requiring more sleep than others

The amount of sleep a person needs is influenced by their genetics. Individual differences in sleep duration and timing are genetically determined, just like eye or hair colour.

Research has shown that the circadian rhythms generated by our internal biological clocks vary from person to person. Some people's internal clocks run slightly longer than 24 hours, while others run slightly shorter. These differences in the speed of the circadian clock may help determine whether you are a "lark" (a morning person) or an "owl" (an evening person).

For example, there is some evidence that if your circadian clock runs faster than 24 hours, you may be more inclined to be a "lark", whereas if your clock runs slower than 24 hours, you may tend to be an "owl".

In addition, some people have a genetic predisposition to be more susceptible to the adverse side effects of sleep loss. For instance, some individuals with a slight genetic variation in one or more genes are much more vulnerable to the negative consequences of sleep loss than the average person.

Furthermore, specific genes have been linked to certain sleep disorders. For example, a 1999 study found that a particular gene causes symptoms in mice and dogs that resemble the symptoms associated with narcolepsy in humans. This gene produces a protein in the brain called orexin or hypocretin, which promotes wakefulness.

Another study, published in 2019, identified a rare mutation in the ADRB1 gene in people who naturally sleep less than six and a half hours each night without any apparent ill effects. This gene codes for the β1-adrenergic receptor, which is found on many cells in the body and responds to hormones that regulate the sleep/wake cycle.

While the exact roles of sleep are still being unpicked, it is known to be involved in memory consolidation and likely gives cells and tissues a chance to rest, regenerate, and clear out waste. A lack of sleep has also been shown to impair the immune system.

In summary, the amount of sleep a person needs is influenced by their genetics, with some people naturally requiring more or less sleep than others due to variations in their internal biological clocks and specific genes related to sleep disorders and sleep duration.

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