What is the reason for short sleep time?

Short sleep time is divided into physiological and pathological, some people sleep time is relatively short than normal people really, often in addition to short sleep, there will be nightmares in sleep, sleep after sleep is relatively shallow, the next day will feel uncomfortable, unable to concentrate, mood is not good, spirit is poor, walk all over the body also has no strength, walk unstable, if show this uncomfortable feeling, need to go to neurology department for treatment. A polysomnogram is usually done to find out which sleep stage shows problems, and then the corresponding sleep hygiene adjustment is given, and medication is given if necessary.