A period of REM sleep normally follows a period of NREM sleep. Insomnia is more common in women and older adults. People who are divorced, widowed, or separated are more likely to have the problem than those who are married, and it is more frequently reported by those with lower socioeconomic status. Short-term, or transient, insomnia is a common occurrence and usually lasts only a few days. Long-term, or chronic insomnia lasts more than three weeks and increases the risk for injuries in the home, at the workplace, and while driving because of daytime sleepiness and decreased concentration.
Chronic insomnia can also lead to mood disorders like depression.
When the situation is resolved or the precipitating factor disappears, the condition goes away, usually without medical treatment. Chronic insomnia usually has different causes, and there may be more than one. Repeated nightmares or panic attacks during sleep. Another cause is excessive worrying about whether or not a person will be able to go to sleep, which creates so much anxiety that the individual's bedtime rituals and behavior actually trigger insomnia. The more one worries about falling asleep, the harder it becomes.