What causes drowsiness? 45 possible conditions

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.

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 reduce 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 anxiety or stress. Boredom is another known cause of drowsiness. If you are experiencing any of these mental conditions, you’re also likely to feel fatigued and suffer from apathy.

Medical Conditions

Some medical conditions can cause drowsiness. The most common is diabetes. Other conditions that may lead to drowsiness include those that cause chronic pain or affect your metabolism, such as hyponatremia (when the level of sodium in your blood is too low), or hypothyroidism. 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 warning against driving or operating 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.

Sleep apnea is a disorder where a blockage in your upper airways creates pauses in your breathing throughout the night, causing you to wake up frequently with a choking sound. Other sleep disorders include narcolepsy, restless leg syndrome, and delayed sleep phase disorder.

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, like working longer hours, or a mental state such as stress.

In these cases, it may help to get plenty of rest and to distract yourself. It’s also important to investigate what’s causing the problem, such as 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 about how well you sleep, and whether you wake up frequently in the night.

Be prepared to answer questions about:

• your sleeping habits
• the amount of sleep you get
• if you snore
• how often you fall asleep during the day
• how often you feel drowsy during the day

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 in the day. They may also ask for specific details, such as if you actually fall asleep in 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 medication without first talking to your doctor.

If no cause for your drowsiness is apparent, you may need to undergo some tests. These are usually noninvasive and painless. Your doctor could request a full blood count, urine tests, an electroencephalogram (EEG), or a computerized tomography (CT) scan.

If your doctor suspects that you may have sleep apnea, restless leg syndrome, 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, breathing, and brain waves 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

Often, a regular amount of sleep each night can 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.

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.