Chronic and persistent difficulty in either (1) falling asleep (initial insomnia), (2) remaining asleep through the night (middle insomnia), or (3) waking up too early (terminal insomnia). All types of insomnia can lead to daytime drowsiness, poor concentration, and the inability to feel refreshed and rested in the morning.

Alternative Names

Insomnia; Inability to sleep; Dyssomnia; Sleeplessness; Wakefulness