Insomnia and daytime functioning.
Results from the present review challenge the assumption that daytime functioning deficits are associated with insomnia. Objectively-measured daytime sleepiness is not elevated in people with insomnia, and most cognitive/psychomotor tasks do not indicate deficits in people with insomnia. In contrast, a number of studies have found that people with insomnia self-report daytime symptoms such as elevated fatigue, mood disturbance and reduced quality of life. Studies including both objective and subjective daytime measures have generally found agreement between the two types of measures, with both typically indicating a lack of daytime impairment. The present review also summarizes evidence suggesting that reported daytime difficulties are produced by factors other than poor sleep, such as physiological or psychological arousal or sleep need misperception.