Excessive daytime sleepiness

Medical quality assurance by Dr. Albrecht Nonnenmacher, MD at January 9, 2017
StartDiseasesExcessive daytime sleepiness

According to the National Sleep Foundation, approximately 20 percent of the population suffers from excessive daytime sleepiness or excessive sleepiness. When it occurs as a primary disorder, it is distinct from fatigue or depression. Excessive daytime sleepiness can be extremely dangerous because it places one at a greater risk of causing an automobile accident. An estimated 40 million people have a sleep disorder of some variety.


Definition & Facts

A person with excessive daytime sleepiness finds it difficult to stay awake during the day. He or she also does not feel refreshed after amounts of sleep that healthy people find adequate. Excessive daytime sleepiness obstructs a person's ability to participate in work and daily activities. It is the leading reason why people pursue treatment at sleep clinics.

Excessive daytime sleepiness can be associated with a primary hypersomnia, or far more commonly, it occurs as a result of other conditions. Examples of the former would include narcolepsy and idiopathic hypersomnia. When excessive daytime sleepiness occurs as a result of other conditions or contributing factors, those secondary causes can include sleep deprivation, other sleep conditions like sleep apnea, side effects of medication, a rotating or nighttime work schedule, poor sleep hygiene, and mental disorders.

Research and treatment of excessive daytime sleepiness can be challenging because there is a lack of clarity and inconsistency on how to best categorize, diagnose, and treat the problem.

Symptoms & Complaints

People with excessive daytime sleepiness feel constantly tired and drowsy. They do not feel refreshed from sleep. They find it difficult to concentrate. They may be confused.

Impaired memory, mood swings, and irritability are other cognitive and behavioral symptoms. Decreases in productivity at work and inability to partake in recreational activities are other symptoms.

A person with this condition may have cardiovascular diseases and weight gain. Sleep-disordered breathing, a cause of excessive daytime sleepiness can increase the risk of venous thromboembolism (this includes pulmonary embolism or deep vein thrombosis). Sleep disorders can also increase the risk of stroke and heart attack.


There are numerous causes of this condition. Narcolepsy is a primary hypersomnia that induces sleepiness. Narcolepsy itself can be caused by genetic factors and environmental factors. In some cases of narcolepsy, there is an autoimmune response that involves antibodies killing a neurotransmitter, hypocretin that helps regulate sleep. Traumatic brain injury is also a contributing factor to narcolepsy and excessive daytime sleepiness more generally.

Secondary causes of excessive daytime sleepiness include sleep deprivation. Adolescents are frequently sleep-deprived, and some studies show that only 15 percent of high school students receive adequate rest on school nights. Sleep deprivation is also common among people working night shifts (shift work sleep disorder). The body's internal clock (its circadian rhythms) are disrupted.

Sleep apnea is another cause of excessive daytime sleepiness. This is a sleep-disordered breathing condition which is also referred to as obstructive sleep apnea and is characterized by periods during which a person stops breathing while sleeping. Sleep apnea can be caused by obesity because excessive fat can obstruct airflow in the respiratory airways.

Medications that affect the central nervous system commonly cause sleep problems. Muscle relaxants, cough medicines (antitussives), antihistamines, anticonvulsants, and antidepressants are examples of some medications that can cause excessive daytime sleepiness. Examples of antidepressants include selective serotonin reuptake inhibitors such as citalopram, fluoxetine, and sertraline.

Benzodiazepines and other anxiolytics (anti-anxiety medications) can cause excessive daytime sleepiness. These include drugs like diazepam, clonazepam, and lorazepam. Drugs that suppress vomiting (antiemetics) and inhibit diarrhea (antidiarrheals) can lead to this condition.

Many of the drugs that can cause sleepiness as a side effect are over-the-counter. In addition to over-the-counter and prescription drugs, illicit drugs like cocaine and marijuana can result in excessive daytime sleepiness. Amphetamines that cause a person to stay up all night for a protracted period may result in excessive daytime sleepiness.

In addition to medications, excessive daytime sleepiness may be the result of mental disorders or psychiatric illnesses. Depression is the most common culprit. Substance abuse is another contributing factor to excessive daytime sleepiness. Brain tumors, head trauma, and encephalitis are other conditions which can cause excessive daytime sleepiness.

Diagnosis & Tests

Diagnosis of excessive daytime sleepiness will necessarily involve establishing symptoms, identifying underlying causes, and ruling out other conditions. A comprehensive inquiry into the patient's medical history, family history, and symptoms are part of the diagnostic process.

A list of any medications or drugs the patient is using will be required to make an accurate diagnosis. The physician will need to know about any over-the-counter, prescribed, or illicit medications the patient is taking or using. A physical examination will also occur.

A variety of tests can help establish the symptoms. The Epworth Sleepiness Scale is a questionnaire which measures how likely a person is to doze off in a variety of different circumstances. The Multiple Sleep Latency Test is another test which can help establish the presence of excessive daytime sleepiness. It measures how quickly a person can fall asleep in a napping context.

Polysomnography or sleep studies are instrumental in diagnosing sleep disorders such as sleep apnea and other abnormalities. These tests record a person's heart rate, brain waves via electroencephalography, and other body functions as a person sleeps. A person's blood oxygen level will be measured during this type of exam. These exams reveal how often a person stops breathing during the night which is an important sign that a person has obstructive sleep apnea. Sleep studies are commonly performed overnight.

Treatment & Therapy

The treatment for excessive daytime sleepiness depends on the underlying cause. If sleep apnea is the cause of this condition, a continuous positive airway pressure (CPAP) machine may assist. A CPAP machine is connected to a mask placed over the patient's face and maintains a continuous flow of oxygen. Nasal strips can help keep the nasal passages open and facilitate better breathing.

There are various medications that can help promote wakefulness. Modanifil is a stimulant that is used to treat excessive daytime sleepiness. Amphetamines are also prescribed to promote wakefulness though can cause significant side effects and have a high risk for abuse.

Prevention & Prophylaxis

Adopting good sleep hygiene can help mitigate or prevent excessive daytime sleepiness. Good sleep hygiene practices include engaging in regular exercise, avoiding nicotine and caffeine particularly close to bedtime, ensuring one is exposed to adequate amounts of sunlight, having a relaxing routine before bedtime, and ensuring that bright electronic screens and devices are turned off.