Drowsiness

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Introduction

What is drowsiness?

Drowsiness refers to feeling sleepy or tired, or being unable to keep your eyes open. Drowsiness, also called excess sleepiness, can be accompanied by lethargy, weakness, and lack of mental agility. While most people feel drowsy at some point or another, persistent sleepiness or fatigue, especially at inappropriate times, can indicate a sleep disorder or other medical problem.

Sleep-wake disorders are a common cause of drowsiness. These include a number of conditions, of which sleep apnea, insomnia, and narcolepsy are the most well known. Sleep apnea is a condition in which you stop breathing in the middle of the night, often several times a night. The deprivation of oxygen, as well as the constant sleep disruption, leads to constant daytime sleepiness, lethargy, and fatigue. It is also associated with more-serious conditions, such as heart disease, diabetes, and obesity. Narcolepsy is a condition characterized by daytime sleep attacks, and insomnia is the perception that you are not getting enough sleep or that the sleep you are getting is poor.

Circadian rhythm sleep disorder occurs frequently in shift workers with fluctuating schedules and the resultant drowsiness can seriously impact family life, job performance and workplace safety.

Depression, stress, and grief are also associated with compromised sleep. Treating or minimizing these conditions can greatly improve the ability to fall asleep and stay asleep. Certain medications are known to cause sleepiness. These include sedatives and tranquilizers, pain medications, and allergy medications, such as antihistamines.

A sudden onset of drowsiness can indicate a life-threatening condition, especially if it is related to a head injury, exposure to extreme cold, or a medication overdose. Seek immediate medical care (call 911) if you, or someone you are with, have experienced a head injury, have taken too much medication or a new medication, or are suffering cold exposure (hypothermia) and become extremely drowsy.

Symptoms

What other symptoms might occur with drowsiness?

Drowsiness may accompany other symptoms, which vary depending on the underlying disease, disorder or condition.

Related symptoms that may occur along with drowsiness

Drowsiness may accompany other related symptoms including:

  • Changes in mood, personality or behavior

  • Difficulty with memory, thinking, talking, comprehension, writing or reading

  • Fatigue

  • Low energy

  • Malaise or lethargy

Other symptoms that may occur along with drowsiness

Drowsiness may accompany symptoms related to other body systems including:

Serious symptoms that might indicate a life-threatening condition

In some cases, drowsiness may be a symptom of a life-threatening condition that should be immediately evaluated in an emergency setting. Seek immediate medical care (call 911) if you, or someone you are with, have any of these life-threatening symptoms including:

  • Change in consciousness or alertness such as passing out or unresponsiveness

  • Change in mental status or sudden behavior change such as confusion, delirium, lethargy, hallucinations or delusions

  • Convulsions or seizures

  • Inability to get warm

  • Severe drowsiness

  • Severe headache

  • Stiff neck

Causes

What causes drowsiness?

Sleep disorders are a common cause of drowsiness. These include sleep apnea, insomnia, and narcolepsy. Sleep apnea is a condition in which you stop breathing in the middle of the night, often several times a night. The deprivation of oxygen, as well as the constant sleep disruption, leads to constant daytime sleepiness, lethargy, and fatigue. It is also associated with more-serious conditions, such as heart disease, diabetes, and obesity.

Certain medications are known to cause sleepiness. These include sedatives and tranquilizers, pain medications, and antiallergy medications, such as antihistamines.

Common causes of drowsiness

Drowsiness can result from common situations or conditions that affect sleep such as:

  • Depression

  • Grief

  • Irregular work schedule such as shift work (circadian rhythm sleep disorder)

  • Stress

  • Travel across time zones (jetlag)

Sleep disorders that cause drowsiness

Drowsiness may be caused by sleep disorders including:

  • Insomnia (insufficient or poor quality sleep)

  • Narcolepsy (sleep disorder characterized by daytime sleep attacks)

  • Sleep apnea (disorder characterized by the interruption of breathing while asleep)

Medications that cause drowsiness

Drowsiness can also be caused by different types of medications including:

  • Anticonvulsants (used to treat epilepsy and seizures)

  • Antidepressants

  • Antiemetics (used to treat nausea)

  • Antihistamines or other allergy medications

  • Sedatives or tranquilizers

Serious or life-threatening causes of drowsiness

In some cases, drowsiness may be a symptom of a serious or life-threatening condition that should be immediately evaluated in an emergency setting. These include:

  • Concussion or head trauma

  • Hypernatremia (excessive levels of sodium)

  • Hyponatremia (low levels of sodium)

  • Hypothermia

  • Medication overdose

Questions for diagnosing the cause of drowsiness

To diagnose your condition, your doctor or licensed health care practitioner will ask you several questions related to your drowsiness including:

  • How long has this drowsiness been occurring?

  • Do you have other symptoms?

  • Have you recently started taking a medication?

  • How much sleep do you typically get?

  • What is your work schedule like?

  • Is your sleep characterized by frequent wakings? Have you been told that you snore?

  • Do you fall asleep often, especially in front of the computer, after lunch, or while watching TV?

  • Do you wake up feeling lively and energized?

  • Do you feel depressed or anxious, or have you recently suffered a loss?

What are the potential complications of drowsiness?

Because drowsiness can be due to serious diseases, failure to seek treatment can result in serious complications and permanent damage. Once the underlying cause is diagnosed, it is important for you to follow the treatment plan that you and your health care professional design specifically for you to reduce the risk of potential complications including:

  • Depression

  • Heart disease

  • Inability to perform daily tasks

  • Poor quality of life

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Medical Reviewer: William C. Lloyd III, MD, FACS
Last Review Date: 2018 Dec 24
  1. Drowsiness. Medline Plus, a service of the National Library of Medicine National Institutes of Health. http://www.nlm.nih.gov/medlineplus/ency/article/003208.htm.
  2. Sleep disorders - overview. PubMed Health, a service of the NLM from the NIH. http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0001803/.
  3. Tierney LM Jr., Saint S, Whooley MA (Eds.) Current Essentials of Medicine (4th ed.). New York: McGraw-Hill, 2011.
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