What Causes Drowsiness?

Conditions list medically reviewed by George Krucik, MD, MBA

Feeling abnormally sleepy or tired during the day is commonly known as drowsiness. Drowsiness may lead to additional symptoms, such as forgetfulness or falling asleep at inappropriate times. Read More

Feeling abnormally sleepy or tired during the day is commonly known as drowsiness. Drowsiness may lead to additional symptoms, such as forgetfulness or falling asleep at inappropriate times.

What are the causes of drowsiness?

A variety of things may cause drowsiness. These can range from mental states and lifestyle choices to serious medical conditions.

Lifestyle choices

Certain lifestyle choices may lead to increased drowsiness, such as working very long hours or switching to a night shift. In most cases, your drowsiness will subside as your body adapts to your new schedule.

Mental state

Drowsiness can also be a result of your mental, emotional, or psychological state.

Depression can greatly increase drowsiness, as can high levels of stress or anxiety. Boredom is another known cause of drowsiness. If you’re experiencing any of these mental conditions, you’re also likely to feel fatigued and apathetic.

Medical conditions

Some medical conditions can cause drowsiness. One of the most common of these is diabetes. Other conditions that may lead to drowsiness include those that cause chronic pain or affect your metabolism or mental state, such as hypothyroidism or hyponatremia. Hyponatremia is when the level of sodium in your blood is too low.

Finally, infectious mononucleosis (mono) and chronic fatigue syndrome (CFS) are other well-known causes of drowsiness.

Medications

Many medications, particularly antihistamines, tranquilizers, and sleeping pills, list drowsiness as a possible side effect. These medications carry a label that warns against driving or operating heavy machinery while consuming these drugs.

Talk to your doctor if you suffer from prolonged drowsiness due to your medications. They may prescribe an alternative or adjust your current dosage.

Sleeping disorder

Excessive drowsiness without a known cause can be a sign of a sleeping disorder. There’s a range of sleeping disorders, and each has its own unique effects.

In obstructive sleep apnea, a blockage in your upper airways leads to snoring and pauses in your breathing throughout the night. This causes you to wake up frequently with a choking sound. Other sleep disorders include narcolepsy, restless leg syndrome (RLS), and delayed sleep phase disorder (DSPS).

How is drowsiness treated?

Treatment of your drowsiness will depend on its cause.

Self-treatment

Some drowsiness can be treated at home, especially if it’s the result of life choices, such as working longer hours, or a mental state such as stress.

In these cases, it may help to get plenty of rest and distract yourself. It’s also important to investigate what’s causing the problem — like if it’s stress or anxiety — and take steps to reduce the feeling.

Medical care

During your appointment, your doctor will try to identify the cause of your drowsiness by discussing the symptom with you. They may ask you about how well you sleep and whether you wake up frequently in the night.

Be prepared to answer questions about:

Your doctor may ask you to keep a diary of your sleeping habits for a few days, documenting how long you sleep at night and what you’re doing when you feel drowsy during the day. They may also ask for specific details, such as if you actually fall asleep during the day and whether you wake up feeling refreshed.

If the doctor suspects that the cause is psychological, they may refer you to a counselor or therapist to help you find a solution.

Drowsiness that’s a side effect of medication is often curable. Your doctor may swap the medication for a different type or change your dosage until the drowsiness subsides. Never change your dosage or stop a prescription medication without first talking to your doctor.

If no cause for your drowsiness is apparent, you may need to undergo some tests. Most are usually noninvasive and painless. Your doctor could request any of the following:

If your doctor suspects that you may have obstructive sleep apnea, RLS, or another sleep disorder, they may schedule a sleep study test. For this test, you’ll spend the night in the hospital or a sleep center under the observation and care of a sleep specialist. Your blood pressure, heart rate, heart rhythm, breathing, oxygenation, brain waves, and certain body movements will be monitored throughout the night for any signs of a sleep disorder.

When to seek emergency care

You should seek medical attention if you begin to feel drowsy after you:

  • start a new medication
  • take an overdose of medication
  • sustain a head injury
  • become exposed to the cold

How can drowsiness be prevented?

A regular amount of sleep each night can often prevent drowsiness. Most adults require about eight hours of sleep to feel fully refreshed. Some people may need more, especially those with medical conditions or a particularly active lifestyle.

Talk to your doctor as soon as possible if you experience any changes in your mood, signs of depression, or uncontrollable feelings of stress and anxiety.

What’s the outlook for untreated drowsiness?

You may find that drowsiness goes away naturally as your body becomes used to a new schedule or as you become less stressed, depressed, or anxious.

However, if the drowsiness is due to a medical problem or sleep disorder, it’s unlikely to get better on its own. In fact, the drowsiness is likely to worsen without proper treatment. Some people manage to live with drowsiness. However, it may limit your ability to work, drive, and operate machinery safely.

Written by Kati Blake


45 possible conditions

This feature is for informational purposes only and should not be used to diagnose. Please consult a healthcare professional if you have health concerns.

Conditions list medically reviewed by George Krucik, MD, MBA