Insomnia

“Insomnia is a symptom that can accompany several sleep, medical and psychiatric disorders, characterized by persistent difficulty falling asleep and/or difficulty staying asleep. Insomnia is typically followed by functional impairment while awake.

Both organic and non-organic insomnia without other cause constitute a sleep disorder, primary insomnia. One definition of insomnia is “difficulties initiating and/or maintaining sleep, or nonrestorative sleep, associated with impairments of daytime functioning or marked distress for more than 1 month….”

“…Acute insomnia is the inability to consistently sleep well for a period of less than a month.”

from wikipedia.com