Sleep InertiaSleep inertia refers to the feeling of grogginess most people experience after awakening. Sleep inertia can last from 1 minute to 4 hours, but typically lasts 15-30 minutes. During this period, you are at a reduced level of capacity and may have trouble doing even simple everyday actions. Usually people fully “wake up” in a half hour at most. For many, the morning routine of a shower or making coffee helps them through the inertial period. Most of the time for most people, sleep inertia is a normal part of life and is nothing to worry about. There are a couple times when it is important, however: 1) If someone has been very sleep deprived or has been woken from a deep sleep stage, the sleep inertia can be more severe than normal and may take longer to overcome. People should try to be aware of their sleep inertia and compensate in their activities for it. Propylactic naps are recommended for people in critical jobs where they must be awake during normal sleep time. When people wake up from naps they often experience sleep inertia. 2) Drowsy driving – a lot of drowsy driving accidents happen early in the morning, not when the driver has been up too long, but when he or she has recently awoken and is still suffering from sleep inertia. Sleep inertia in a driver behind the wheel can be very dangerous as the impairment of motor and cognitive functions and can affect a person's ability to drive safely. Many factors are involved in the characteristics of sleep inertia. The duration of prior sleep can influence the severity of subsequent sleep inertia. Although most studies have focused on sleep inertia after short naps, its effects can be shown after a normal 8-h sleep period. A critical factors is the sleep stage prior to awakening. Awakening during a stage 3 or 4 sleep produces more sleep inertia than awakening in stage 1 or 2. Waking up during REM sleep is in between. Many people experience sleep inertia even after short naps. When a person has been sleep deprived, sleep inertia can last longer, even after a full night’s sleep. When there has not been sleep deprivation, the sleep inertia rarely lasts more than 30 minutes. Although it is a transitional state between sleep and wakefulness, there is no evidence that sleep inertia exhibits a circadian rhythm. The inertia is stronger when the awakening occurs near the trough of the core body temperature as compared to its peak, but this is consistent with inertia being worse when the person wakes from stage 3 and 4. Morning Grogginess“Grogginess” doesn’t have a precise medical or scientific meaning, but we all know what it is: not being fully awake or at normal performance after a sleep. Sleep inertia is the preferred term among professionals. Everyone has groggy mornings at least once in a while, but we all differ in how we wake up and start the day. “Morning people” rarely experience grogginess, or if they do for very long. Others have grogginess every day. This could be classified as the sleep disorder Delayed Sleep Phase Syndrome. Some sleeping aids cause morning grogginess, too, although this is more common with old style sleeping pills like Halcion than the newer pills. A study published in the Journal of the American Medical Association in 2006 found that severe morning grogginess can be more dangerous and debilitating than staying up all night. They're both dangerous, of course, but it is important that people with bad grogginess do something to remedy it before they get behind the wheel. The job search website Monster.com published a list of 10 Ways to Shake Grogginess. While some of these seem reasonable, it is less likely that reading a newspaper will help you overcome grogginess, and the idea of driving with the windows open is clearly a bad idea when you are not fully awake. Experts on drowsy driving warn that rolling down the windows is not an effective countermeasure.
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ResourcesAvoiding Drowsy Driving
Countermeasures
Responsibility and the Drowsy Driver
Signs of Drowsiness when Driving
How Well Are You Sleeping? - FDA Consumer Article Circadian gene helps brain predict mealtime Sleep less, live longer? - Increased Death Rate
Associated Circadan Rythyms
"And miles to go before I sleep" (Robert Frost, Stopping by Woods on a Snowy Evening)
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