Have you ever felt like you needed a nap during the day after having had a short amount of sleep at night or an intense start of the day? You might have wondered whether it’s beneficial or not to do so.
There is still controversy on the amount of sleep we need each night. While a well-known quota says we need around 7.5 hours, the amount appears to be rather an individual matter, differing greatly between people. For example, when we get older the sleep we need is slightly reduced. Moreover, the functions that recover appear to differ over hours slept as I will explain below.
A study investigating the effects of a short nap (45 minutes) to improve performance on several aspects after a night with reduced sleep. They compared 3 groups, a group who slept a full night without napping, one that had half a night of sleep, and a group with half a night of sleep and a short nap. They found that the short nap improves performance on motor and memory tasks, however not to levels comparable to that with a full night of sleep. Moreover, it is seen that motor memory recovery happens mostly after several hours of sleep, thus sleeping for a shorter period will lead to reduced motor memory performance. Other than increased sleep length, the amount of sleep spindles was also important for motor memory performance, and many sleep spindles were observed during the nap. Sleep spindles are short bursts of electromagnetic activity, can be measured using EEG. This activity is thought to be important for a big variety of things, ranging from memory consolidation to cognitive development. This means that by the increase of sleep spindles during shorter sleep, there is a mechanism in place to protect motor memory.
While I initially set out to investigate the question whether we could break up our sleep rhythm into fewer blocks of sleep (a strategy called the Uberman sleep cycle), there was too little scientific literature on this topic, so I reshaped the article. However, I do believe that based on what I discussed we can argue it might be disadvantageous to use the Uberman sleep cycle, as the sleep conditions that are important for motor memory occur as we sleep longer (post 3.5 hours of sleep). Thus, while we sleep, different aspects recover or get processed in our brain. Taking a nap after lacking some hours during the night can act as a band-aid, there is nothing that can compete with a full night of sleep.
Author: Kobus Lampe
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