Is excessive sleepiness a sign of a dangerous disease?
Frequent sleepiness or drowsiness can be a sign of dangerous diseases.
The key to overcoming excessive sleepiness is identifying its cause. A healthcare professional can help you explore other symptoms, possible causes, and next steps to increase your energy and alertness.
Any condition that prevents you from getting enough quantity and quality of sleep
Both can lead to excessive sleepiness.

In general, excessive daytime sleepiness is not the only symptom you experience. Other symptoms that may accompany it include snoring and restlessness while you sleep. You may not be aware of some of these symptoms.
Some causes of excessive sleepiness are not usually related to disturbances in the sleep-wake cycle but also lead to daytime sleepiness. For example, thyroid disorders or cancer.
Here are some common causes of excessive sleepiness:
Sleep apnea
Sleep apnea is a serious condition in which you repeatedly stop and start breathing throughout the night. This condition is one of the reasons why you feel sleepy during the day.
Symptoms of sleep apnea include:
- Loud snoring and gasping for air while sleeping
- Sore throat and headache when waking up
- Reduced attention and concentration
- Irritable
Sleep apnea increases your risk of:
- High blood pressure
- Heart disease
- Type 2 diabetes
- Obesity
Sleep apnea can cause excessive sleepiness because it prevents you from getting enough sleep.
Depression:
A noticeable change in your sleep habits is a common symptom of depression. You may sleep more or less than you used to.
Other symptoms of depression include low motivation, frequent irritability, changes in appetite, feeling hopeless, and losing interest in favorite activities.
If you don't sleep well at night, you may feel excessively sleepy during the day. Sometimes sleep changes are an early sign of depression. For others, changes in sleep habits occur after other signs of depression appear.
Depression has many potential causes, including abnormal levels of certain brain chemicals, problems with areas of the brain that control mood, and traumatic events.
Side effects of the drug:

Some medications have side effects that cause excessive drowsiness, which may include medications to treat:
- High blood pressure
- Depression
- Nasal congestion (antihistamines)
- Nausea and vomiting (antiemetics)
- Mental disorders
- Epilepsy
- Anxiety
If you think your prescription medication is making you sleepy, talk to your doctor about finding a solution that helps. It is important not to stop taking any medication without the supervision of your healthcare professional.
Aging:
Older adults typically need more sleep but have the lowest quality sleep. According to experts, aging is associated with changes in the circadian cycle that result in less time spent in the deep sleep stage of the cycle and more frequent waking in the middle of the night.
Chronic physical and mental conditions can also make it difficult to sleep through the night and lead to excessive daytime sleepiness.
Idiopathic insomnia:
When a health care professional can't identify a clear cause for your excessive sleepiness, they may diagnose idiopathic insomnia (IH). Idiopathic means there's no clear cause for your symptoms.
IH is a chronic sleep disorder that involves persistent excessive sleepiness despite getting enough sleep or even for long periods of time. You may also have difficulty waking up from sleep.
What substance deficiency in the body causes excessive sleepiness?

Low levels of iron and B complex vitamins in the blood can sometimes lead to excessive sleepiness and fatigue. Diets that are low in essential nutrients—like protein, healthy fats, and carbohydrates—can also leave you feeling sleepy and lacking in energy.
Only a healthcare professional can assess whether your symptoms are related to a nutritional deficiency.
How to overcome excessive sleepiness:
Managing excessive sleepiness begins with identifying possible causes. Your healthcare professional will be able to assist you. Depending on the findings, they will recommend specific management options including medication, dietary changes, increased physical activity, or talk therapy, among others./.