Cognition and sleep: the effects of poor sleep on cognition
Medicine is well aware of the harmful effects that poor quality sleep has on our health. But scientists still don’t know very well how it affects our health. cognitionIt’s also important for our memory and our ability to concentrate. The truth is that we need to sleep an average of 8 hours a day, except for the little and big sleepers, which means that we spend a third of our lives sleeping, and quality sleep is just as important for our health as eating well and practicing regular physical activity.
In this content, prepared by our experts, we’ll talk about the relationship between cognition and sleep: the effects of poor sleep on cognition. What are the consequences of poor sleep on our health? cognition? Did you know that research has linked irregular sleep to the effects of alcohol on the brain? Find out now, the influence of poor sleep on cognition.
What is cognition
From Latin congnosewhich means to know, cognitionin its broadest definition, is everything related to knowledge. Cognition is the ability we have to process information through perception, assimilating and processing information we obtain from the most diverse sources, such as our perceptions, our experiences, beliefs, readings, conversations and so on.
According to the definition in the Michaelis dictionary, cognition is “the act or effect of knowing; the process of acquiring knowledge; knowledge; a set of conscious mental processes based on sensory experiences, thoughts, representations and memories”.
A cognition is made up of various cognitive processes, including learning, attention, memory, language, reasoning and decision-making, which help us to develop intellectually. A cognition is widely studied by neurology, psychology, anthropology and philosophy. But it is cognitive psychology, which emerged in the late 1950s, that studies and analyzes it in greater depth, assessing how the information process influences our behavior and what the relationship is between different mental processes and knowledge.
Interest in cognition Neuroimaging has grown a lot since the 1960s, and authors such as biologist Jean Piaget and psychologist Lev Semionovich Vigotsky have contributed greatly to its understanding. Advances in the field of neuroimaging bring deeper psychological and neuroanatomical knowledge, allowing science to better understand mental processes and their influence on our behavior and emotions.
What are sleep disorders?
To talk and understand a little more about cognition and the influences that poor quality, non-restorative and insufficient sleep can have on it, it is also important to talk about sleep disorders. In a nutshell, sleep disorders are diseases that directly affect the quality of sleep on a regular basis.
The most well-known sleep disorders are insomniasleep apnea, night terrors, narcolepsy, sleepwalking, restless legs syndrome and bruxism, among others. These sleep disorders rob us of quality of life, causing tiredness, irritation, mood swings, sleepiness throughout the day, difficulty concentrating, a drop in work and study performance and headaches, but they can also lead to even more serious consequences, such as depression, stroke or even cardiovascular disease.
Sleep disorders, the result of regular nights of poor sleep, have a direct effect on our health. cognitionAnd that’s what we’re going to talk about now.
Sleep vs. brain function
How and how much can the quality of our sleep influence the way our brain works? Scientists from the Departments of Psychiatry and Neuropsychiatry in South Korea decided to find an answer to this question through the study “Sleep and Cognitive Decline: A Prospective Non-demented Elderly Cohort Study”, published in 2018 in Annals of Neurology, a renowned medical journal dedicated to publishing and disseminating scientific articles on neurology. The researchers’ main objective was to deepen knowledge and understanding of the relationship between sleep quality and the development of cognitive disorders in the elderly.
For four years, the quality of sleep and its changes in cognitive function of 2,893 people aged 60 and over with cognition normal (NC) or mild cognitive decline (MCD) were assessed individually. Average sleep time, age, gender, education, depression, cumulative illness rating scale (CIRS), socioeconomic status, work, smoking, physical activity, sleep disorders and sleep apnea were assessed.
Results and conclusion
The results of research participants with cognition normal (NC) have shown that individuals with long sleep duration, who take longer to fall asleep or who have the middle phase of sleep (the time when half of the total sleep duration occurs) at later times are associated with a higher prevalence of cognitive decline when compared to subjects with healthier sleep.
In participants with cognitive decline, it was observed that individuals who took longer to fall asleep (long sleep latency) had 30% less chance of reversing the cognitive deficit when compared to individuals whose short sleep latency, sleep duration and baseline half-sleep phase were not associated with cognitive changes.
The researchers also found that long sleep latency in the group with cognitive impairment did not affect the incidence of dementia, which led them to believe that this may not be a risk factor, but rather an early sign of dementia in the patients. Among participants with normal cognition, long sleep duration increased the risk of incidence of cognitive decline by 1.7 times.
The scientists’ conclusion was:
– Long sleep latency can be used as an early marker of cognitive decline for elderly people with normal cognition and those with cognitive impairment.
– Increased sleep duration and a delayed half-sleep phase can only be used as markers for elderly people with normal cognition.
It’s worth remembering that it’s not just the length of sleep that should be taken into account for a restorative night’s sleep. The quality of sleep must also be taken into account. An individual with a long duration of poor quality sleep may sleep worse than an individual with a short duration of good quality sleep. To understand more about these aspects, it is advisable to monitor your sleep routine using actigraphy.
The consequences of lack of sleep on the brain
To demonstrate the consequences of lack of sleep on our brains, the Brain and Mind Institute at Western University in Canada is carrying out extensive research, coordinated by British neuroscientist Adrian Owen, into the consequences of lack of sleep on the brain with thousands of volunteers from all over the world. The scientists believe they will be able to determine an average number of hours needed to optimize brain function, although the need for sleep is absolutely individual.
A quick experiment was carried out with five volunteers, who spent a night at the university: one psychiatrist a 31-year-old mother of two young girls, a 75-year-old retired security guard, a 31-year-old neuroscientist who does cognitive research with mice at night, which requires her to work at night, and a BBC journalist. During the experiment, they carried out four tests on computers, tablets and smartphones.
The group stayed awake until 4 a.m., then were allowed to sleep for four hours, when the tests were repeated first thing in the morning. The journalist, the retired security guard and the neuroscientist performed much worse than they had the night before. The psychiatrist’s performance barely changed, but that of the girls’ mother improved. She said she was very used to waking up and immediately being asked for a lot by her daughters.
The researchers took a CT scan of the journalist’s brain at the same time as he repeated the tests. His brain was scanned twice, after a normal night’s sleep and after a bad night’s sleep. The comparison of the images showed that the lack of sleep resulted in very low brain activity, with less activity in the frontal and parietal lobes, which are areas of our brain that are fundamental for decision-making, problem-solving and memory.
In another study in which the sleep duration of the participants was controlled, it was observed that after 14 days of sleep restriction, individuals who slept 6 hours or less, had cognitive deficits similar to those of subjects who spent 24 hours without sleep, and could reach a cognitive deficit similar to that of subjects who spent 3 days in total sleep deprivation!
How does sleep help the brain reorganize itself?
Research published in the prestigious scientific journal Nature Communications shows that regular, quality sleep has positive consequences and helps our brain to organize itself, which is fundamental for our health. cognition. According to the research, resting the brain through a good night’s sleep has a positive impact on memory and learning in everyday life.
According to the research, activity in the dendrites (a specific region of neurons) is intensified, and this structure is fundamental to the nervous system’s ability to change and meet new demands. The research showed that the increased performance of the so-called dendrites is closely linked to the “spindles”, brain waves emitted when we sleep, which influence the formation of memories.
“Sleep spindles have been associated with memory formation in humans for some time, but no one knew what they were actually doing in the brain. Now we know that during spindles, specific pathways are activated in dendrites, perhaps allowing our memories to be reinforced during sleep. Our brains are amazing and fascinating organs, they have the ability to change and adapt based on our experiences. It is becoming increasingly clear that sleep plays an important role in these adaptive changes and our study shows that a large proportion of these changes can occur during spindles,” said the study’s leader, researcher Julie Seibt, from Survey University.
The scientists used laboratory rats to measure the levels of calcium ions in the dendrites and measured the frequency of “spindles” using an electroencephalogram. They were able to observe that the increase in electrical flow in the dendrites coincides with a greater occurrence of “spindles”. This is when the process of reorganizing the brain takes place, which proves the good effects of a good night’s sleep on our health. cognition.
Bad sleep: impact on the brain is the same as that caused by alcohol
An important and revealing study entitled “Selective neuronal lapses precede human cognitive lapses following sleep deprivation” (“Selective neuronal lapses precede human cognitive lapses after sleep deprivation”), published in the respected scientific journal NatureAccording to a new study, poorly slept nights can result in memory lapses and distorted visual perception due to a temporary communication failure between neurons. According to the researchers who led this study, the effects can be similar to drunkenness.
The study was conducted by researchers from the University of Los Angeles in the United States and Tel Aviv University in Israel on 12 volunteers with epilepsy. Electrodes were implanted in their brains to record how often the seizures occurred and where they originated. It was decided to induce seizures through sleep deprivation. In other words, the participants had to stay awake during the night until they had a seizure episode, and had to perform small cognitive tasks such as sorting images into categories as quickly as possible.
The scientists assessed brain activity in the temporal lobe, which is associated with memory and visual recognition. The more tired and sleepy the participants were, the more difficult it was for them to perform the tasks. According to the researchers, lack of sleep reduces the ability of our neurons to function, which can cause lapses in our memory. cognition. Sleep deprivation, the research pointed out, affects the way neurons encode information and how visual stimuli are read, something very similar to the consequences of alcohol consumption.
This group of researchers is extending the study, now focusing on understanding the brain mechanisms responsible for lapses in memory and perception and the benefits of a good night’s sleep.
Sleep disorders and actigraphy
Of course, we all eventually have a bad night’s sleep, and we know all too well how difficult the next day is because of it. But when this happens regularly, you need to investigate what’s going on, and you’re probably suffering from a sleep disorder. The main cause of irregular nights’ sleep is some kind of sleep disorder.
An important and revealing test that can be ordered by a doctor for those with some kind of sleep disorder is actigraphy. Through actigrapherIn this way, it is possible to follow the cycles of activity and rest, capturing, compiling and processing information to study the rhythm of sleep and wakefulness and the consequences of sleep disorders. circadian rhythm.
More modern actigraphs have temperature and light sensors, allowing for a greater depth of data analysis. This is a test often requested by doctors, especially sleep doctorsThis can help to identify the diagnosis and thus indicate the treatment to be carried out.
Conclusion
You don’t have to be a scientist, a doctor or a psychologist to realize how bad a night’s sleep (or sleep deprivation) is for us. But the repetition of this condition can affect our health in a drastic way. It is not yet known exactly why an irregular night’s sleep affects our cognition, but research has identified this direct relationship between cognition and sleep.
The truth is that a restorative night’s sleep is fundamental to our health, just as it is absolutely important to eat well and exercise regularly – every doctor will agree with this, without exception. The various neurobiological processes that take place during sleep are fundamental to maintaining our physical and cognitive health, including emotion and memory. Studies linking cognition and sleep: the effects of poor sleep on cognition show that sleep deprived people have significantly worse cognitive activities, which means a lower performance capacity.
