Study, Sleep, Repeat
This timeline will be familiar to those of you who have experienced an all-nighter. During the first 16 hours of day 1, you feel normal. Your attention span and working memory have not yet been affected. Then, around hour 17, you enter your “biological night time.” The hormone melatonin, which circulates from your brain to your body, reaches a peak level that signals to your body that it is night-time. This is when your performance rapidly deteriorates and reaches a minimum around 6 to 8am the next morning. While your performance may improve throughout the following day, it will remain below that of day one until you get a decent amount of sleep. This timeline of your performance is regulated by your internal biological time of day; it is not a linear deterioration based on the number of hours you have been awake.
A team of researchers used functional magnetic resonance imaging (fMRI), a noninvasive technique used to measure and map brain activity by detecting changes in blood oxygenation and flow, to scan the brains of 33 people who were sleep deprived over two days and following a period of recovery sleep. The participants’ levels of melatonin were also measured to determine each person’s internal biological time. Brain images were taken during a reaction time task, sleep deprivation in the evening and morning when performance undergoes rapid changes, and after recovery sleep. The results showed some variation in the timing of the 24-hour circadian rhythm that is followed by some brain regions, including subcortical areas such as the thalamus, which is responsible for relaying sensory information from receptors in the body to the cerebral cortex. The frontal brain regions showed a decrease in activity during sleep deprivation and a return to regular levels of activity after recovery sleep. The effects of sleep deprivation were also evident in participants’ performances in simple reaction time tasks.
While sleep deprivation affects various brain regions differently, its effects are pervasive. Hence, you should try to sleep between study sessions so your brain has a chance to consolidate the information you studied, and you can be at your top performance level to continue studying or to take your final the next day.
~ Sophia Hon