Sleep inertia is a physiological state of impaired cognitive and sensory-motor performance that is present immediately after awakening. It is the groggy feeling upon waking, caused by abrupt disruption of sleep. Sleep inertia generally lasts for 15 to 60 minutes but may last for up to a few hours after waking. The symptoms of sleep inertia include feelings of drowsiness, disorientation, and a decline in motor dexterity. Impairment from sleep inertia may take several hours to dissipate, and it poses an occupational hazard due to the cognitive and motor deficits that may be present. Sleep inertia is not a sleep disorder, but people with certain sleep disorders are more likely to experience more severe or longer-lasting sleep inertia. Researchers hypothesize that sleep inertia is a protective mechanism that helps maintain sleep during moments of unwanted wakings.
Strategies that may help cope with sleep inertia include caffeine, exposure to bright light, and physical activity. Caffeine can help shake off some of the effects of sleep inertia. Exposure to bright light can help reset the bodys internal clock and promote wakefulness. Physical activity can also help promote wakefulness and reduce the effects of sleep inertia.
