Sleep inertia
Sleep inertia is a physiological state characterised by a decline in motor dexterity and a subjective feeling of grogginess immediately following an abrupt awakening. The impaired alertness may interfere with the ability to perform mental or physical tasks. Sleep inertia can also refer to the tendency of a person wanting to return to sleep.
Sleep inertia occurs normally after awakening. Upon awakening in the morning, subjective alertness and mental performance are significantly impaired. Morning sleep inertia may take several hours to dissipate. In the majority of cases, morning sleep inertia is experienced for 15 to 30 minutes after waking.
Factors
Studies by the Human Factors Division at NASA Ames Research Center have shown that a variety of factors influence the severity and duration of sleep inertia. These include:
