Daytime Sleepiness: Why Do I Feel So Sleepy?

Feeling sleepy during the day is known as hypersomnia, a condition that affects 5% to 10% of people in the United States. People with hypersomnia experience excessive daytime sleepiness, falling asleep repeatedly throughout the day, even during activities like eating or talking. This can be caused by a variety of factors, including underlying medical conditions, sleep disorders, mental health issues, lifestyle factors, and medications. Hypersomnia can impact an individual's ability to function at work and socially, affecting their quality of life and increasing the risk of accidents. Treatment options include medications, non-drug therapies, and lifestyle changes such as improving sleep hygiene and maintaining a consistent sleep schedule.

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

Sleep disorders such as sleep apnea, restless leg syndrome, and insomnia can all cause excessive daytime sleepiness. People with insomnia are more likely to have a car crash due to fatigue, and lack of sleep is the cause of over 7% of serious accidents in the workplace. Insomnia can also increase the risk of other health problems, including obesity due to eating foods high in calories. Sleep affects our ability to think, react, remember, and solve problems, and people with insomnia tend to feel more tired than sleepy, struggling to get through normal daily activities.

Sleep apnea is a condition in which a person's breathing stops or is reduced during sleep, sometimes as often as every minute. The brain registers the breathing problem and briefly wakes the person to gasp for air before they fall back to sleep. As a result, sleep is fragmented, and people with sleep apnea may feel the need to nap during the day.

Restless leg syndrome causes sensations of cramps or irritation in the legs, particularly the calves, compelling people to move their legs or get out of bed and walk around. This disrupts sleep and can lead to excessive daytime sleepiness.

In addition to these sleep disorders, there are other factors that can contribute to feeling sleepy during the day. Environmental factors such as a snoring partner, a baby that wakes up frequently, noisy neighbours, uncomfortable temperatures, or an uncomfortable mattress can all lead to broken sleep. Shift work, long working hours, family demands, and social life can also result in inadequate sleep. Mental states such as anxiety and depression can impact sleep, and certain medications and medical conditions can disrupt sleeping patterns.

Lifestyle factors, including diet, dehydration, and poor sleep habits

Lifestyle Factors

Diet

A diet high in fat is associated with increased daytime sleepiness, while a diet high in carbohydrates is associated with increased alertness. This is the case even when controlling for factors such as age, gender, body mass index, total caloric intake, and the amount of sleep.

Dehydration

Dehydration can also cause daytime sleepiness. The body needs a precise ratio of electrolytes, including minerals like potassium, calcium, and sodium, to retain and balance fluid inside and outside of cells. Dehydration can cause nocturnal leg cramps, limb movement, and discomfort that causes you to wake up throughout the night. It can also affect melatonin, a sleep hormone that plays a key role in regulating your natural sleep cycle.

Poor Sleep Habits

Poor sleep habits can lead to insufficient sleep and cause you to feel sleepy during the day. This can be caused by shift work, family demands, study, or social life. Environmental factors such as a snoring partner, a baby that wakes up, noisy neighbours, uncomfortable temperatures, or an uncomfortable mattress can also lead to broken sleep.

Mental states can also cause poor sleep. Anxiety can keep a person awake at night, making them prone to sleepiness during the day, and depression saps energy.

Medical conditions, like hypothyroidism, chronic fatigue syndrome, and depression

Daytime sleepiness can be a symptom of several medical conditions, including hypothyroidism, chronic fatigue syndrome, and depression.

Hypothyroidism

Hypothyroidism is a medical condition that occurs due to a decrease in thyroid hormone production, resulting in an underactive thyroid. Fatigue is a nearly universal symptom of hypothyroidism, and it can develop slowly or come on suddenly. People with hypothyroidism may sleep more than usual but still feel exhausted and may not have enough energy to exercise. They often require a nap during the day and find it difficult to get out of bed in the morning. Hypothyroidism can also lead to disrupted sleep patterns and unintentional weight loss. Adjusting thyroid medication under medical supervision can help relieve the fatigue associated with hypothyroidism.

Chronic Fatigue Syndrome

The relationship between chronic fatigue syndrome (CFS) and daytime sleepiness is not yet fully understood. While CFS patients experience fatigue, it is unclear if they also exhibit daytime sleepiness. One study found that CFS patients showed lower objective sleepiness than those with sleep apnea-hypopnea syndrome (SAHS), a condition characterised by excessive daytime sleepiness. However, CFS patients reported higher subjective fatigue than those with SAHS.

Depression

Excessive daytime sleepiness (EDS) is commonly reported among depressed patients across many populations. EDS can be a predictor of and a risk factor for depression. Depressed individuals with EDS may experience drowsiness, reduced performance, and involuntary sleep despite their efforts to stay awake. They are also at an increased risk of accidents. The presence of EDS in depressed patients may be due to shared genetic factors, as there is evidence of heritability of daytime sleepiness and depressive symptoms. Proper clinical evaluation of EDS in cases of depressive illness is essential, as EDS in depression may respond to energizing antidepressants.

Mental health issues, such as anxiety and bipolar disorder

Anxiety can cause a hormonal rush that leaves you feeling drained and tired. The feeling of exhaustion can last even after you've rested. It can be challenging to fall asleep or stay asleep due to anxiety, leading to disrupted sleep patterns and increased daytime sleepiness. The relationship between sleep and anxiety is complex and bidirectional: anxiety can disrupt sleep, and lack of sleep can, in turn, increase anxiety. This cycle can be challenging to break, and chronic anxiety and fatigue often go hand in hand.

Additionally, panic attacks, which are common in panic disorder (a type of anxiety disorder), can be physically draining, further contributing to feelings of fatigue. Other physical symptoms of anxiety, such as a racing heart and quickened breath, can also be tiring.

Bipolar disorder is characterised by extreme emotional mood swings, including manic episodes of highs and depressive episodes of lows. During a manic episode, insomnia and restlessness are common, leading to fatigue and tiredness during the day. The shift from mania to depression can be sudden, and the depressive episode can bring exhaustion due to low energy and sleep disturbances.

To manage fatigue associated with mental health issues, lifestyle changes, therapy, and medications can be beneficial. Establishing a healthy sleep routine, regular exercise, a balanced diet, and relaxation techniques are often recommended. Additionally, seeking professional help from a therapist or healthcare provider is crucial, especially if anxiety or fatigue interferes with daily life.

Medication and substance use, including alcohol, caffeine, and prescription drugs

Alcohol, for instance, is known to have a sedative effect that can make you drowsy and help you relax, which may seem like a good way to fall asleep faster. However, this effect is only temporary, and once the body starts to metabolise the alcohol, it can lead to disrupted sleep and frequent waking. Alcohol reduces REM sleep, the deepest stage of sleep associated with restoration, memory, and concentration. As a result, you may experience grogginess the next day and even an increased risk of disease and early death. Additionally, alcohol can worsen sleep-related breathing problems, such as sleep apnea, and increase the need to urinate during the night, further disrupting your sleep.

Caffeine, on the other hand, is a stimulant that can keep you awake and interfere with your sleep. It is important to limit caffeine intake, especially close to bedtime, as it can affect your ability to fall asleep and impact your overall sleep quality.

Prescription drugs can also cause sleepiness during the day. Certain medications, such as tranquilisers, sleeping pills, antihistamines, and antidepressants, can disrupt your sleep patterns and make you feel drowsy during the day. It is important to be aware of the potential side effects of any medications you are taking and consult your doctor if you have concerns.

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