Daytime Sleep: Why Is It So Difficult?

There are many reasons why you might be struggling to sleep during the day. One of the most common reasons is a disruption to your circadian rhythm, which is your body's internal clock. This can be caused by various factors such as jet lag, shift work, delayed sleep phase syndrome, or advanced sleep phase syndrome. Other reasons could include poor napping habits, anxiety, depression, caffeine consumption, blue light from electronic devices, sleep disorders such as sleep apnea and restless leg syndrome, diet, or even your pet's sleep habits.

Shift work sleep disorder

The average person with SWSD loses one to four hours of sleep per night, and the disorder can lead to significant complications, including mood problems, poor work performance, higher accident risk, added health problems, low testosterone, and substance abuse.

The prevalence of SWSD is estimated to be between 2% and 10% of the general population and about 27% of night and rotating shift workers. The disorder often goes undiagnosed, and it is estimated that 10-40% of shift workers experience it.

There are several risk factors associated with SWSD, including age, gender, and genetic predisposition. The highest prevalence is in the 50 years old and above age bracket, and females may be more susceptible due to social obligations and expectations.

Treatment options for SWSD include bright light therapy, melatonin supplements, and medications that promote alertness or daytime sleep. Creating a consistent sleep schedule, a relaxing sleep environment, and practising good sleep hygiene can also help mitigate the effects of the disorder.

If left untreated, SWSD can have serious consequences on an individual's health, well-being, and work performance, highlighting the importance of recognising and addressing the disorder.

Delayed sleep phase disorder

DSPS is characterised by a shift in one's biological clock, which makes it difficult to fall asleep and wake up. It is considered a circadian rhythm sleep disorder, as it affects the body's natural 24-hour cycle that regulates periods of sleep and wakefulness, as well as other functions like body temperature and digestion.

The disorder is commonly seen in adolescents and young adults, with a prevalence of around 7 to 16 percent in these age groups. It may develop in early childhood but often emerges or worsens during adolescence. In some cases, adolescents may delay their sleep schedules for social reasons, and their sleep patterns normalise in early adulthood. DSPS is also observed in adults, particularly women and people assigned female at birth between the ages of 40 and 60.

People with DSPS typically have trouble falling asleep unless they go to bed very late, usually after midnight. This is because their internal clock is sending alerting signals until late into the night. Consequently, they also struggle to wake up at a "normal" time in the morning due to their internal clock not yet producing strong alerting signals.

The condition can lead to severe daytime sleepiness and changes in mood and behaviour. It may also result in impairment in social, occupational, or other areas of life. Over 60% of people diagnosed with DSPS experience depression, and many also develop a substance use disorder, relying on caffeine, sedatives, or alcohol to stay awake or fall asleep.

Treatment for DSPS aims to reset the individual's internal clock. Bright light therapy and chronotherapy are two common approaches used by sleep specialists. Bright light therapy involves using light to gradually shift the person's sleeping pattern to a more conventional schedule. Chronotherapy, on the other hand, aims to reset the circadian clock by slowly delaying bedtime and the sleep period by about two hours every few days.

Caffeine consumption

Caffeine is a stimulant and the most widely consumed in the world, with 90% of American adults consuming caffeine-infused beverages almost daily. Caffeine promotes wakefulness by blocking adenosine, a sleep-inducing chemical.

Caffeine affects the brain by blocking adenosine receptors. Adenosine is a sleep-promoting chemical that is produced in the brain during our waking hours. Normally, adenosine builds up in the brain the longer you are awake. The more it builds up, the sleepier you become. When caffeine blocks this process, you remain alert and vigilant.

Caffeine has a half-life of anywhere between 2 and 12 hours. A drug’s half-life refers to the amount of time it takes for your body to metabolize and eliminate half the dose you consumed. The range is so wide because many individual factors affect how quickly you metabolize caffeine and how soon its effects wear off. For example, nicotine use can shorten the half-life of caffeine by up to 50%, so frequent smokers eliminate caffeine from their body more quickly.

Caffeine can make it difficult to fall asleep and reduce the amount of deep, slow-wave sleep you get, which is a critical stage of sleep for feeling refreshed the next day. It is generally recommended to avoid consuming caffeine in the hours leading up to bedtime to minimize the risk of insomnia and to promote better sleep quality. People with chronic insomnia may find it helpful to try reducing or eliminating caffeine intake or only consuming it early in the day as strategies for improving sleep.

The generally recommended cut-off time for caffeine use is a minimum of eight hours before bedtime. For example, if you typically go to bed at 10 pm, avoiding caffeine after 2 pm may help minimize sleep problems.

Blue light from devices

Electronic devices such as smartphones, tablets, and computers emit significant amounts of blue light, a type of light that has been linked to sleep disturbances. During the day, exposure to blue light can be particularly disruptive to sleep patterns.

Blue light is a short-wavelength light that is beneficial during the day as it boosts attention, mood, and cognitive function. However, in the evening and during the night, it can be detrimental. This is because blue light suppresses the production of melatonin, a hormone that regulates sleep and wake cycles. When exposed to blue light during the day, the body's natural sleep-wake cycle can be disrupted, making it more difficult to fall asleep at night.

The impact of blue light on sleep is particularly notable when using devices at night, close to bedtime. The use of electronic devices in the hours before sleep can delay the body's internal clock, suppress melatonin secretion, and shift sleep and wake cycles, all of which contribute to sleep disturbances.

To mitigate the impact of blue light on sleep, it is recommended to reduce exposure to electronic devices and screens in the evening and at night. This can be achieved by setting a bedtime schedule that involves turning off devices at a certain time, or by using blue light filters or night modes on devices, which help reduce the amount of blue light emitted.

Additionally, increasing exposure to natural light during the day can be beneficial. This helps regulate the body's sleep-wake cycle and can reduce the impact of blue light exposure during the daytime. Regular exposure to sunlight, especially in the morning, can help improve sleep quality and promote wakefulness during the day.

Sleep disorders

• Insomnia: Insomnia is a sleep disorder characterised by difficulty falling asleep or staying asleep throughout the night. It can be caused by stress, anxiety, depression, poor sleep habits, circadian rhythm disorders (such as jet lag), medications, or underlying medical conditions.
• Circadian Rhythm Disorders: These disorders occur when an individual's sleep-wake cycle is misaligned with their internal "clock," which is driven by the suprachiasmatic nucleus in the brain. Examples include jet lag, shift work adjustments, delayed sleep phase syndrome, and advanced sleep phase syndrome.
• Sleep Apnea: Sleep apnea is a serious sleep disorder where breathing is interrupted during sleep due to a blocked airway. It can cause severe daytime sleepiness and is associated with an increased risk of high blood pressure, stroke, and heart attack if left untreated.
• Narcolepsy: Narcolepsy is a brain disorder that causes excessive daytime sleepiness. While some patients experience dramatic sleep attacks, others simply feel constant sleepiness throughout the day. There may be a genetic component, but many patients have no family history of the disorder.
• Restless Legs Syndrome (RLS): RLS causes an urge to move the legs and feet, typically in the evening and night, to relieve discomfort. This can delay sleep onset and cause brief awakenings during sleep. It is commonly seen in middle-aged and older adults and can be caused by various factors, including nerve disorders, vitamin deficiencies, and pregnancy.
• Nightmares and Night Terrors: Nightmares are frightening dreams that occur during REM sleep and can be caused by stress, anxiety, or certain medications. Night terrors are more common in young children but can also affect adults experiencing emotional or psychological problems. They often involve screaming or thrashing around without being able to explain the fear.

In addition to these sleep disorders, other factors can impact sleep quality. For example, diet, exercise, and exposure to light and temperature can influence sleep. Spicy foods, caffeine, and nicotine consumption can also disrupt sleep patterns. Additionally, our sleep can be affected by our sleep environment, such as the comfort of our bedding, exposure to light and noise, and the presence of pets or bed partners.

Frequently asked questions