A large-scale study on the association between daily sleep duration and cognitive performance led to interesting findings. Those, now with good statistical power, support an earlier hypothesis about an optimal number of nighttime sleep hours that is good for our brain function. A step left or right, with shorter or longer sleep duration, and cognitive performance suffers.
The fact of sleep deprivation causing cognitive deficits, along with other unwanted effects, is consistent with common knowledge. All of us have experienced negative effects of either acute or chronic lack of sleep. Since science is yet to learn the ultimate mystery of sleep – its physiological purpose – there is no scientific explanation of the mechanisms that lead to such effects of sleep deprivation. However, there are many hypotheses regarding the principal sleep function and some are focused on neuronal plasticity. Cognitive performance depends on neuronal plasticity and thus it can link sleep and cognition.
Even less clear is how excessive sleep could interfere with cognitive functions. Perhaps, sleep duration and cognition may correlate with yet another common condition, such as depression, metabolic abnormality or other disorders. For example, when we suffer flu, inflammation and fever correlate with a number of other symptoms, sleepiness and poor cognitive functions being among them.
This new study reminds us how important sleep is and that more research is needed to uncover its mysteries and help those suffering from sleep disorders.