Sleep inertia

• "Grogginess", as defined by a drowsy or disoriented state in which there is a dampening of sensory acuity and mental processing. • Impaired motor dexterity and decrease in cognitive ability. These gross impairments may be responsible for the associated increase in reaction time and drop in attentiveness. • Reports of heightened subjective fatigue • Reduced vigilance and a desire to go back to sleep These symptoms are expressed with the greatest intensity immediately after waking, and dissipate following a period of extended wakefulness. The duration of symptoms varies on a conditional basis, with primary expression during the first 15–60 minutes after waking and potentially extending for several hours. ==Causes==

Studies have shown that abrupt awakening during stage 3 sleep, slow-wave sleep (SWS), produces more sleep inertia than awakening during sleep stages 1, 2 or REM sleep. Prior sleep deprivation increases the percentage of time spent in slow-wave sleep (SWS). Therefore, an individual who was previously sleep deprived will have a greater chance of experiencing sleep inertia. Individuals express a lack of blood flow to the brain upon awakening. Levels of cerebral blood flow (CBF) and cerebral blood flow velocities (CBFV) will take up to 30 minutes to increase and reach daytime levels. == Treatments and countermeasures ==

There has been a great deal of research into potential methods to relieve the effects of sleep inertia. The demand for remedies is driven by the occupational hazards of sleep inertia for employees who work extended shifts such as medical professionals, emergency responders, or military personnel. The motor functioning and cognitive ability of these professionals who must immediately respond to a call can pose a safety hazard in the workplace. Below are some of the various methods that have been suggested to combat sleep inertia. Napping When a person is sleep deprived, re-entering sleep may provide a viable route to reduce mental and physical fatigue, but it can also induce sleep inertia. In order to limit sleep inertia, one should avoid waking from the deeper stages of slow-wave sleep. The onset of slow-wave sleep occurs approximately 30 minutes after falling asleep, therefore a nap should be limited to under 30 minutes to prevent waking during slow-wave sleep and enhancing sleep inertia. Furthermore, self-awakening from a short nap was shown to relieve disorientation of sleep inertia as opposed to a forced awakening, but these results may warrant more research into the nature of arousal after sleep periods. ==See also==