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Sleep Disorders

Excessive sleepiness



One of my good friends, is always tired. She doesn`t have symptoms of most of the sleep disorders. She just is always tired and can sleep for more than 13 hours at a time. She won`t admit that something is wrong but I know that I don`t have that problem nor do any other people I know. I`m worried about her. Yesterday she complained to me that she had a feeling of extreme weakness so she had to call off work. Thanks for any help you can give me.


When someone is tired, it could be that he or she is sleepy or fatigued. The distinction between sleepiness and fatigue is important since the causes are often different. To tell the two apart, a rule of thumb would be that fatigue gets worse with activity and better with rest, while sleepiness gets better with activity and worse with rest. Often this distinction is not easy and the person may have a combination of the two. Since your friend may sleep more than 13 hours at a time, it's an indication that she has an element of sleepiness, at least.

Causes of sleepiness are variable but can be lumped into 3 major categories:

1- Insufficient sleep: Insufficient sleep is by far the most common cause of sleepiness in our current 24/7 community. While sleep duration needs are different between individuals (range from 5 to 9 hours), most people function well on 7 hours of sleep per night. If you are getting less than what you usually need, you will eventually have a recovery period of longer-than-usual sleep episode. This is known as (weekend crash) among those who work long hours during the week, and sleep-in until late during the weekend.

2- Disturbed sleep: Many medical, psychiatric, and environmental conditions cause the quality of sleep to be suboptimal. Sleep apnea is the most common. In sleep apnea a person stops breathing multiple times during the night and has many short arousals throughout their usual sleep period. Sleep fragmentation may not obvious to the person. A bed partner is more likely to notice these episodes. Sleep out of rhythm with the usual body tendency can be also disturbed and non-refreshing. Most often, this is seen in shift workers.

3- Abnormal transitions between wake and sleep: When sleep intrudes into wakefulness abruptly, or during unexpected times of the day, this can be seen as excessive sleepiness. Some people have wakefulness activities that occur during their sleep, like sleep walking and sleep talking, but this seems unrelated to your friend's current problem.

Causes of fatigue, on the other hand, are not easy to categorize. A general list includes:

I apologize for not having more specific information in this reply. Your friend needs a clinical evaluation. It is important that she is seen by a physician if these complaints are not temporary and if they do not resolve with enough sleep. An evaluation by a Sleep Specialist may become necessary if sleepiness is suspected.

If you'd like additional information regarding sleep and sleep disorders, you may obtain it on the American Academy of Sleep Medicine website. This website also contains a list of Sleep Centers across the country so you can locate one near you if need it. Good luck, and may you both sleep well.

For more information:

Go to the Sleep Disorders health topic, where you can:

Response by:

Ziad  Shaman, MD Ziad Shaman, MD
Assistant Professor of Medicine
School of Medicine
Case Western Reserve University