Definition and Overview

Also referred to as hypersomnia, excessive daytime sleepiness (EDS) is a type of sleeping problem that refers to the uncontrollable urge to sleep during the day making sufferers becoming more active at night.

The body has its own clock (sometimes called the body clock) that helps regulate a variety of activities, such as the release of hormones. It is characterized by oscillation, fluctuation, or dips and lows. Although genes can affect the function of this clock, the environment a person is in can also play a huge role.

For instance, the body’s clock is influenced by the light the eyes can perceive. The suprachiasmatic nucleus or SCN, which forms part of the brain, sits very close to the optic nerves, which transmit visual signals to the brain. When it “sees” darkness, the SCN then begins the production of melatonin, which helps the person feel more relaxed and ready to fall asleep.

Sleep is an incredibly important body process. A person who lacks sleep will develop cognitive impairment, memory loss, and even mood and behavior changes. He or she can become more irritable or grumpy, making him or her a hard person to deal with.

Physically, poor sleep can decrease the body’s immunity, increase weight, and decrease sex drive. Those who often lack sleep are at risk of developing cardiovascular disease and diabetes.

Causes of Condition

  • Chronic Stress – Chronic stress refers to the persistent feeling of being under stress. This can lead to many nights of restless or poor sleep, forcing the body to compensate for the lack of it by extending sleepiness in the morning.

  • Pain – A person who is under physical and emotional pain usually ends up sleep-deprived. The pain is usually enough to keep them awake for the rest of the night.

  • Sleep apnoea – Sleep apnoea is characterized by a loud snoring. In many cases, the sound can be so loud it drives the person to wake up in the middle of the night, thereby cutting back on good-quality sleep.

  • Narcolepsy – This is a rare neurological disorder that is characterized by excessive daytime sleepiness as the sufferer’s brain lacks the ability to regulate sleep-wake patterns effectively. Thus, he or she can fall asleep suddenly at any time of the day. Those who have experienced this for a long time can somehow feel when it’s coming at least a few seconds before falling asleep, but more often than not, its onset is sudden. This places a person at a greater risk of injury or even death.

  • Cataplexy – Cataplexy is a condition characterized by a sudden loss of muscle control triggered by a surge of emotion such as laughter or anger. A person with cataplexy can collapse and end up falling asleep. The condition is also more common among those who have been diagnosed with narcolepsy.

  • Myxedema – This is a life-threatening condition that develops due to a complication from an underactive thyroid. This simply means that the thyroid glands, which are butterfly-shaped glands located just above the voice box, release fewer hormones than they should. A person with myxedema develops wax-like consistency on the skin due to the swelling of the tissues as well as cold intolerance, lethargy and drowsiness.

  • Shifts – Working in shifts can disturb the body’s circadian rhythm.

  • Medications – Certain medications can disrupt a person’s sleep-wake patterns by making him or her fall asleep even during the day.

  • Insomnia – Insomnia is a sleeping disorder that makes it difficult for the sufferer to stay asleep or fall asleep.

  • Huge meals – Some people may feel sleepy or drowsy after every big meal such as breakfast. This happens because of certain hormones, namely, glucose and melatonin. As the body consumes more food, the pancreas releases more insulin, which also boosts melatonin production.

Key Symptoms

It’s perfectly normal to feel sleepy early in the morning or throughout the day especially if you did not get a good sleep the night before. However, a person should seek the help of a health care provider if the drowsiness is accompanied by:

  • A chronic feeling of lethargy and exhaustion
  • A sudden loss of muscle control
  • Difficulty fighting off sleep
  • Unconsciousness
  • Intolerance to changes in body temperature
  • Mood and behavior changes
  • Difficulty in remembering or storing information
  • Feeling of drowsiness even after getting enough sleep
  • Symptoms of diabetes such as high levels of insulin or glucose in the blood

Who to See and Treatments Available

The best person to diagnose excessive daytime sleepiness is a sleep specialist or a general practitioner. Fortunately, many health care facilities these days have laboratories that can be helpful in diagnosing the problem.

A variety of tests can be conducted to diagnose sleeping problems, including blood, urinalysis, and polysomnography, a test that measures the brain activity or brainwaves while a person is asleep. Aside from the brainwaves, the level of oxygen in the blood and limb movements will also be measured.

The treatment, meanwhile, depends on the cause. The first step to avoiding drowsiness or EDS is to ensure that the patient receives a good amount of sleep. This can be achieved by:

  • Following a standard wake-time pattern (this means falling asleep at night)
  • Turning the lights off at night
  • Keeping any devices with lights such as mobile phones or tablets outside the bedroom
  • Reducing stress
  • Eating a healthy balanced diet
  • Avoiding strenuous activities at night

Condition-related drowsiness, on the other hand, can be treated depending on the diagnosis. A person with narcolepsy, for instance, may be prescribed stimulants and antidepressants while a person suffering from sleep apnea may be treated using CPAP or continuous positive airway pressure.


  • Sateia MJ. International classification of sleep disorders-third edition: highlights and modifications. Chest. 2014;146:1387-1394. PMID 25367475

  • Wakefield TL, Lam DJ, Ishman SL. Sleep apnea and sleep disorders. In: Flint PW, Haughey BH, Lund VJ, et al., eds. Cummings Otolaryngology: Head & Neck Surgery. 6th ed. Philadelphia, PA: Elsevier Mosby; 2015:chap 18.

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