Everyone knows that not getting enough sleep makes it hard to perform at the top of your game.  Being overtired impacts your cognitive abilities, making it harder to concentrate and slowing your response time.  It compromises your decision making capabilities and impulse control.  Sleep deprivation, the complete lack of sleep, has been studied extensively and the effects on our bodies and minds are fairly well understood. Research has shown that going without sleep for even a single day can lead to impairment on par with intoxication.

While these findings are important and provide significant insight for those in the field of sleep medicine, these studies don’t mimic or recreate the conditions faced by the majority of sleepy people.    Most people who are struggling with sleep are not going without sleep for days on end; they are only getting some of the sleep they need every night.  For these people, the challenge is more about sleep restriction than sleep deprivation.  This is why a team of researchers chose to look at how the affects of sleep restriction compare to those seen with sleep deprivation.

Restricted sleep, which occurs when someone routinely gets significantly less sleep than they need, is one of the most common reasons that adults experience sleep loss.  It is commonly seen in shift workers, new parents, and people who work odd or excessive schedules.  As getting some sleep, but not enough sleep most closely mirrors how many people are living their lives, the objective of the study was to see if there was a difference in the level of impairment displayed by participants if they were deprived of sleep for a single night or if their sleep was restricted over several nights.

In order to answer this question, the team gathered a group of healthy males aged 46 to 55 to participate in the study.  The 18 participants all slept normally the first night of the study.  On the second night, some of the participants were completely deprived of sleep in order to capture the effects of acute sleep deprivation.  The remainder of the group was only allowed to sleep for four hours the second through sixth nights in order to capture the effects of chronic sleep restriction.  Each participant completed a series of tests designed to gauge their level of sleepiness, ability to perform cognitive functions, and reaction times at different points in the study.  To wrap-up the study, each participant spent one additional night sleeping normally.

The team made some interesting observations.  First, both groups were immediately impacted by their sleep loss and displayed a degradation of performance during the testing.  It only took two nights of restricted sleep for the level of performance degradation to be the same as getting no sleep at all.  However, the group experiencing sleep restriction seemed to adapt to the decreased amount of sleep after three days and their sleep loss no longer seemed to impact their performance.  Additionally, a single night of sleeping 8 hours was completely restorative for both groups.

These findings suggest that our bodies may automatically adjust when faced with chronic sleep restriction, allowing us to function almost normally after only three days.  While this doesn’t erase the long term consequences of chronic sleep restriction to our overall health, it does provide some insight into why so many of us can get by without getting enough sleep.


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