* Circadian rhythm sleep disorders cause insomnia at some times of the day and excessive sleepiness at other times of the day. Common circadian rhythm sleep disorders include jet lag and delayed sleep phase syndrome. Jet lag is seen in people who travel through multiple time zones, as the time relative to the rising and falling of the sun no longer coincides with the body’s internal concept of it. The insomnia experienced by shift workers is also a circadian rhythm sleep disorder.
* Parasomnia includes a number of disorders of arousal or disruptive sleep events including nightmares, sleepwalking, violent behavior while sleeping, and REM behavior disorder, in which a person moves his/her physical body in response to events within his/her dreams. These conditions can often be treated successfully through medical intervention or through the use of a sleep specialist.
* Gastroesophageal Reflux Disease; causes repeated awakenings during the night due to unpleasant sensations resulting from stomach acid flowing upward into the throat while asleep.
* Mania or Hypomania; in bipolar disorder can cause difficulty falling asleep. A person going through a manic or hypomanic episode may feel a reduced need for sleep. Sleep deprivation can worsen a manic episode, or cause hypomania to develop into mania.
* Stimulants; like caffeine, nicotine, sugar, certain medicines, or other pills/drugs