Daytime Sleep: Why Less Is More

Sleep is a vital part of our lives, accounting for one-quarter to one-third of our lifespan. However, many people struggle with excessive daytime sleepiness, or hypersomnia, which can impact their daily activities and overall health. This condition is characterised by regular napping and sleeping for long hours, even during the day. While the specific causes vary from person to person, hypersomnia can be influenced by factors such as inadequate sleep, sleep disorders, medications, and medical or psychiatric illnesses. Understanding and addressing these underlying causes through lifestyle adjustments and medical treatments are crucial steps towards managing hypersomnia and improving sleep quality.

Sleep disorders, such as sleep apnea, restless legs syndrome, and insomnia

Sleep Apnea

Obstructive sleep apnea (OSA) occurs when the tissue in the back of the throat relaxes during sleep, partially blocking the airway. This can cause you to stop breathing periodically throughout the night, leading to snoring, gasping for air, and sore throat or headaches upon waking up. Central sleep apnea (CSA), on the other hand, is caused by the brain failing to send the correct nerve signals to the muscles controlling breathing during sleep. Sleep apnea can disrupt your sleep and cause excessive daytime sleepiness, as well as affect your concentration and attention.

Restless Legs Syndrome (RLS)

RLS causes an irresistible urge to move one's legs due to uncomfortable sensations like throbbing or itching. This can make it challenging to fall asleep or stay asleep, resulting in daytime sleepiness. While the exact causes are unknown, RLS may be linked to genetic factors, low iron levels, or issues with the brain's basal ganglia, which controls movement.

Insomnia

Insomnia is characterised by difficulty falling or staying asleep, early awakening, or unrefreshing sleep. It can be a standalone disorder or a symptom of other disorders, such as mental health conditions. Insomnia can be caused by intrinsic factors, such as physical pain or discomfort, or extrinsic factors, such as caffeine consumption, irregular sleep schedules, or emotional stressors. Acute emotional stressors, like job loss or a death in the family, can lead to transient insomnia, while chronic insomnia may be linked to mental health disorders like depression.

Treatment Options

The treatment for these sleep disorders varies. For sleep apnea, continuous positive airway pressure (CPAP) therapy is commonly used, involving a small machine that pumps air through a flexible hose to a mask worn over the nose and mouth. For RLS, lifestyle measures like leg massages, warm baths, and early-day exercise can help. Iron supplements may also be recommended if low iron levels are a contributing factor. Insomnia treatment depends on the underlying cause but may include cognitive-behavioural strategies, sleep hygiene improvements, and, in some cases, hypnotics or antidepressants.

Mental health, including anxiety and depression

Sleep and mental health are closely linked. Poor sleep can negatively impact mental health, and mental health issues can affect sleep quality and duration. This bidirectional relationship is particularly evident in individuals struggling with anxiety and depression.

Anxiety

Anxiety disorders can cause racing or repetitive thoughts and worries that make it difficult to fall or stay asleep. The anxiety may manifest as panic attacks while trying to sleep. Sleep deprivation studies have shown that healthy individuals experience increased anxiety and distress levels following poor sleep.

Depression

Depression and sleep problems often co-occur, with insomnia being a common symptom of depression. Sleep issues may influence the function of the neurotransmitter serotonin, which is implicated in depression. Sleep disruptions can affect the body's stress system, further increasing vulnerability to depression.

Depression can lead to fragmented sleep, resulting in excessive daytime sleepiness and fatigue. Individuals with depression may find it challenging to regulate their sleep-wake cycle, experiencing both insomnia and hypersomnia during a single depressive episode.

Treatment Approaches

Treating sleep problems can help alleviate symptoms of anxiety and depression. Cognitive-behavioural therapy for insomnia (CBT-I) has been found to improve sleep in individuals with these mental health disorders. Additionally, addressing underlying mental health conditions can contribute to better sleep quality.

Medication and substance use, including alcohol and caffeine

The use of medication and substances, including alcohol and caffeine, can significantly impact sleep quality and duration.

Alcohol

Alcohol is known to disrupt sleep, even in moderate amounts. It can cause frequent wakings and low-quality sleep, with individuals experiencing more deep sleep initially and more light sleep later in the night. Alcohol can also negatively impact sleep architecture, contributing to sleep disorders and interfering with circadian rhythms. It can worsen snoring and sleep apnea, affecting breathing during sleep. Additionally, heavy alcohol use can lead to insomnia, and conversely, people with insomnia may turn to alcohol as a sleep aid, creating a destructive pattern. Alcohol also interferes with circadian rhythms, reducing the body's sensitivity to cues like daylight and darkness, which are essential for the sleep-wake cycle.

Caffeine

Caffeine is a well-known stimulant that can significantly disrupt sleep, even when consumed several hours before bedtime. It reduces total sleep time and increases sleep latency, or the time it takes to fall asleep. Caffeine's effects are more pronounced when consumed in the afternoon or evening, leading to sleep fragmentation and reduced sleep duration. Caffeine's impact on sleep may be underestimated, and its consumption should be restricted to earlier in the day to minimise sleep disturbances.

Medication

Various medications can also affect sleep. Antidepressants, for example, can have varying effects, with some being stimulating and others sedating. Beta-blockers can interfere with sleep by decreasing melatonin levels. Decongestants can be stimulating, raising blood pressure and heart rate, and may cause insomnia. Diuretics can interrupt sleep by increasing the need to urinate during the night. Smoking-cessation drugs, including nicotine replacement products and prescription medications, can cause unusual dreams and nightmares, disrupting sleep. Oral steroids, such as prednisone, can disrupt the sleep cycle by stimulating the production of cortisol, a stress hormone.

It is important to consult a healthcare professional if you suspect that your sleep issues are related to medication use. They may advise adjusting the timing, dosage, or type of medication to improve sleep quality.

Environmental factors, like noise or light

Noise

Noise is a common environmental factor that can affect the quality of sleep. Noisy environments can make it difficult to fall asleep and stay asleep, leading to sleep deprivation and daytime sleepiness. Sources of noise can include loud neighbours, traffic, construction work, or even a snoring partner. Shift workers, especially those working at night, are particularly vulnerable to noise disturbances as they try to sleep during the day when ambient noise levels tend to be higher.

Light

Light plays a crucial role in regulating our sleep-wake cycles. Our bodies respond to light cues, triggering the production of melatonin, the hormone that helps us sleep, in low-light conditions. However, during the day, when natural light is more abundant, our bodies suppress melatonin production, making it challenging to fall asleep. This is especially true for individuals who work night shifts and need to sleep during the daytime when sunlight can interfere with their rest.

Additionally, the excessive use of electronic devices with bright screens can also impact sleep. The blue light emitted by smartphones, tablets, and computers can suppress melatonin production and delay the onset of sleep, making it harder to fall asleep at night and leading to daytime sleepiness.

Temperature

Temperature fluctuations can also impact sleep quality. Both heat and cold can disrupt sleep, causing restlessness and discomfort. During the day, when temperatures tend to be higher, it can be challenging to create a cool and comfortable sleeping environment, leading to fragmented sleep and daytime sleepiness.

Uncomfortable mattress or bedding

An uncomfortable mattress or bedding can also contribute to disrupted sleep. If your mattress is too firm or too soft, or if your bedding doesn't provide adequate support or temperature regulation, you may find yourself tossing and turning instead of sleeping soundly. This can result in non-restorative sleep and daytime sleepiness.

To improve sleep quality, it is essential to address these environmental factors as much as possible. This may include soundproofing your bedroom, using earplugs, investing in blackout curtains or a comfortable mattress, and maintaining a cool temperature in the bedroom. By creating a peaceful and comfortable sleeping environment, you can enhance your sleep quality and reduce daytime sleepiness.

Biological factors, such as age and genetics

Ageing is associated with changes in the quality and duration of sleep. These changes are due to alterations in the body's internal clock, which is located in a part of the brain called the hypothalamus. This internal clock, known as the suprachiasmatic nucleus (SCN), controls 24-hour daily cycles called circadian rhythms, which influence when people feel sleepy or alert. As the SCN deteriorates with age, it can disrupt these circadian rhythms, affecting sleep patterns. Older adults may experience a phase advance, where they get tired earlier in the afternoon and wake up earlier in the morning. They may also spend more time in the early, lighter stages of sleep and less time in the deeper stages, leading to more frequent awakenings and fragmented sleep.

Additionally, older adults often have insufficient exposure to daylight, which can further disrupt their circadian rhythms. Changes in hormone production, such as decreased melatonin secretion, can also contribute to sleep disturbances. Lifestyle changes that come with ageing, such as retirement and social isolation, can impact sleep quality as well.

While the recommended sleep duration for adults remains relatively consistent across age groups, with seven to eight hours of sleep being advised for those over 65, ageing can affect sleep patterns in various ways. Medical conditions, medications, and a lack of physical activity can all contribute to sleep problems in older adults.

Genetics also plays a role in sleep patterns, and researchers have identified genes that influence the amount of sleep individuals need. For example, a gene called "wide awake" in fruit flies affects their ability to fall asleep and stay asleep. A similar gene exists in humans and mice, and its study is ongoing. Additionally, a rare mutation in the ADRB1 gene has been linked to shortened sleep cycles in humans, with those carrying the mutation sleeping for less than six and a half hours each night without apparent ill effects.

The DEC2 gene mutation causes short sleepers to stay awake longer, while the NPSR1 mutation alters neurotransmitters in the human brain, resulting in reduced sleep. Individuals with these genetic variations often exhibit ambitious, type A personalities and have excellent memories. They tend to be driven, optimistic, and productive, taking advantage of the extra time afforded by their shorter sleep cycles.

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