by Twenty-six years. That is roughly how much of our life is spent sleeping. Scientists have been trying to explain why we spend so much time sleeping since at least the ancient Greeks, but the exact functions of sleep have been difficult to pin down.
Over the past decade, there has been a surge of interest from researchers in the nature and function of sleep. New experimental models along with advances in technology and analytical techniques are giving us a deeper look inside the sleeping brain. Here are some of the biggest recent developments in sleep science.
1. We know more about lucid dreaming
No longer on the fringes, the neurological study of dreaming has now become mainstream.
US researchers in a 2017 study woke up their participants at regular intervals during the night and asked them what was going on in their minds before the alarm call. Sometimes the participants were unable to recall any dreams. The study team then looked at what was happening in the participant’s brain moments before they woke up.
Participants’ memory of dream content was associated with increased activity in the posterior cingulate, an area of the brain closely associated with conscious awareness. Researchers could predict the presence or absence of dream experiences by monitoring this zone in real time.
Another exciting development in the study of dreams is research into lucid dreaming, in which you know you are dreaming. A 2021 study established two-way communication between dreamer and researcher. In this experiment, participants signaled to the researcher that they were dreaming by moving their eyes in a pre-agreed pattern.
The researcher read out math problems (what is eight minus six?). The dreamer could answer this question with eye movements. The dreamers were accurate, indicating that they had access to higher level cognitive functions. The researchers used polysomnography, which monitors body functions such as breathing and brain activity during sleep, to confirm that the participants were asleep.
These discoveries have dream researchers excited about the future of “interactive dreams”, such as practicing a skill or solving a problem in our dreams.
Read more: While we dream, we can listen to the waking world – podcast
2. Our brain replays memories while we sleep
This year marks the centenary of the first demonstration that sleep improves our memory. However, a 2023 review of recent research showed that memories created during the day are reactivated while we sleep. Researchers discovered this by using machine learning techniques to “decode” the contents of the sleeping brain.
A 2021 study found that training algorithms to distinguish between different memories while awake could see the same neural patterns re-emerging in the sleeping brain. A different study, also in 2021, found that the more times these patterns reoccur during sleep, the greater the benefit to memory.
In another approach, scientists were able to reactivate certain memories by playing back sounds associated with the memory in question while the participant was asleep. A 2020 meta-analysis of 91 experiments found that when participants’ memory was tested after sleep, they remembered more of the stimuli whose sounds were played back during sleep, compared to control stimuli whose sounds were not played back. sounds.
Research has also shown that sleep strengthens memory for the most important aspects of an experience, restructures our memories to form more coherent stories and helps us find solutions to problems we’re stuck on. Science shows that sleep helps him a lot.
3. Sleep keeps our minds healthy
We all know that lack of sleep makes us feel bad. Laboratory sleep deprivation studies, in which researchers keep willing participants awake all night, have been combined with functional MRI brain scans to paint a detailed picture of the sleep-deprived brain. These studies have shown that lack of sleep greatly affects the connectivity between different brain networks. These changes include a breakdown of connectivity between brain regions responsible for cognitive control, and an amplification of those involved in threat and emotional processing.
The result of this is that the sleep-deprived brain is worse at learning new information, worse at controlling emotions, and unable to suppress intrusive thoughts. You may be less likely to help sleeping with others. These findings may explain why poor sleep quality is so ubiquitous in poor mental health.
4. Sleep protects us against neurodegenerative diseases
Although we naturally sleep less as we age, increasing evidence suggests that sleep problems earlier in life increase the risk of dementia.
An increase in β-amyloid, a metabolic waste product, is one of the underlying mechanisms of Alzheimer’s disease. Recently, it has become clear that deep, undisturbed sleep is good for flushing these toxins out of the brain. Sleep deprivation increases the rate of β-amyloid accumulation in parts of the brain associated with memory, such as the hippocampus. A longitudinal study published in 2020 found that sleep problems were associated with a higher rate of β-amyloid accumulation four years later. In a different study, published in 2022, sleep parameters predicted the rate of cognitive decline in participants over the following two years.
5. We can engineer sleep
The good news is that research is developing treatments to get better sleep and boost its benefits.
For example, the European Society for Sleep Research and the American Academy of Sleep Medicine recommend cognitive behavioral therapy for insomnia (CBT-I). CBT-I works by identifying thoughts, feelings and behaviors that contribute to insomnia, which can then be modified to promote sleep.
In 2022, the CBT-I app was the first digital therapy recommended by England’s National Institute for Health and Care Excellence for treatment on the NHS.
These interventions can also improve other aspects of our lives. A 2021 meta-analysis of 65 clinical trials found that improving sleep through CBT-I reduced symptoms of depression, anxiety, rumination and stress.
This article from The Conversation is republished under a Creative Commons license. Read the original article.
Dan Denis receives funding from the European Union’s Vision 2020 research and innovation program under Marie Skłodowska-Curie grant agreement No. 101028886.
