by Cristina Marrone
Sleeping even one night for less than six hours can compromise short-term memory and make it difficult to concentrate: here’s what happens to the brain
What happens when you get little or no sleep? You feel exhausted, irritable, with great difficulty concentrating and carrying out complex tasks. Sleep deprivation can hinder your ability to draw on memories and form new ones. Even a single night with less than six hours of sleep can compromise short-term memory the following day according to scientific literature. In fact, sleep debt interferes with the ability of neurons to encode information and thus translate visual input into conscious thought. In other words, when you are tired your brain cells are unable to communicate with each other, which explains why you experience temporary memory lapses, such as forgetting your keys in the morning or leaving the house without your phone.
Extreme sleep deprivation
Not everyone reacts the same way to sleep deprivation but, in general, the longer you go without adequate rest, the greater the load on your brain. Extreme sleep deprivation – staying awake for more than 24 hours – can lead to people behaving as if they were drunk. An experiment conducted years ago on three volunteers (one was a professor at the University of Philadelphia) kept awake for between 50 and 90 hours showed that, apart from muscle weakness, they all lost the ability to concentrate, two of them did not remember nothing of what had happened even just moments before, one was hallucinating. And by the end of the experiment all three had gained weight.
What happens to the brain when you sleep little
While a person rests the brain strengthens and synthesizes the connections between neurons that have formed during the previous day and this helps to store the recurrences, a process known as consolidation. According to experts, REM sleep plays a particularly important role in maintaining memories: during REM sleep, very complex neuronal networks are activated, involved in the consolidation of memories. «When people do not get enough rest and wake up before they are fully rested, they sleep less overall and are likely to also miss the last and longest period of REM sleep, which occurs in the last hours of rest. And this is why you can feel nervous, anxious, irritable and it’s easy to not remember some things” Dr. Indira Gurubhagavatula, sleep specialist at Penn Medicine University, tells the New York Times. In the brain, these changes manifest as less activity in the prefrontal cortex, which is responsible for planning, decision making and other executive functions. At the same time, greater activity is observed in the amygdala, the area of the brain involved in feelings of fear and anxiety. Sleep deprivation can also activate the sympathetic nervous system, which presides over the “fight and flight” adaptation system, preparing the body to face danger, thus making us feel stressed and nervous.
Difficulty paying attention and memorizing
When you sleep little, there may be difficulties in paying attention to what is in front of you (think of a lecture at university) and this obviously makes memorization more difficult. The same thing applies when you feel anxious or worried: the mind is not fully present and this can limit the amount of information encoded by the brain. As a result, you may have difficulty remembering details of conversations or events that occurred when you are tired and sleep-deprived. It’s not so strange, for example, not to remember where you parked your car. «Research shows that people who sleep less than they need have slower response times, difficulties in decision-making and attention and worsening of memory» confirms Carlotta Mutti, neurologist at the Hospital’s Sleep Medicine Center of Parma. For this reason, risky behaviors that could endanger oneself and others should be avoided, such as getting behind the wheel: reflexes are in fact slowed down.
Short-term memory
Short-term sleep deprivation does not affect deeply held information: Even when you are endlessly tired, most people remember biographical details that they have known for many years, such as the city where you were born or the street where you live. . The problem concerns the most recent information, acquired during the period of sleep deficit. Sleeping less than necessary can have a negative impact on the frontal lobe of the brain: it is an area involved in memory recovery and executive functions (a set of skills that include the ability to multitask and make decisions).
A large study of more than 479,000 adults aged 38 to 73 found that people who said they typically slept between three and six hours performed worse on cognitive tests aimed at measuring their executive function than people who slept between six and eight hours. These tests included tasks that involved working memory, which refers to the brain’s ability to retain and use a small amount of information, such as remembering the content of a sentence you just read or what was written on the grocery list. Furthermore, the study found that the cognitive performance of those who regularly slept between three and six hours decreased further for every hour of sleep lost. To compensate for the effects of a sleepless night, it may take several nights of deep sleep. Afternoon naps can be refreshing, provided, however, in this case, that you do not reach deep sleep (therefore they must not exceed 30 minutes). Finally, with age it becomes increasingly difficult to recover from bad nights: the older you become, the more difficult it is to rest (and make up for lost sleep).
March 1, 2024
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