How much sleep is necessary to be alert and healthy? Four neuroscientists reveal the findings of their research
Most of us struggle to think well after a poor night’s sleep – feeling foggy and failing to perform at our usual standard at school, university or work. You may notice that you’re not concentrating as well, or that your memory doesn’t seem up to scratch. Bad sleep habits over many years can lead to cognitive decline.
Bad sleep also affects people’s mood and behaviour, whether they are young infants or older adults. How much sleep does the brain require to function well over the long term? Our new research study, published in Nature AgingThe answer is in the following:
Sleep is essential for maintaining normal brain function. Sleep is crucial for the brain to reorganise and recharge itself. As well as removing toxic waste byproducts and boosting our immune system, sleep is also key for ‘memory consolidation’, during which new memory segments based on our experiences are transferred into long-term memory.
A good quality and quantity of sleep can help you have more energy and better well-being. It allows us to grow our creativity and think more clearly.
Researchers have found that babies aged three to twelve months old are more likely to get better sleep than those who were born earlier. better behavioural outcomes in the first year of lifeThis includes being able to adapt to new situations and regulating emotions effectively.
These are important early building blocks for cognition, including ‘cognitive flexibility’ (our ability to shift perspective easily), and are linked to wellbeing in later life.
Sleep regularity seems to be linked to the brain’s ‘default mode network’ (DMN), which involves regions that are active when we are awake but not engaged in a specific task, such as resting while our mind wanders. This network includes areas that are critical for cognitive function such as the posterior cortex (which is activated during cognitive tasks), the parietal and frontal cortex (which process sensory info) and the frontal cortex, which are involved in planning and complex cognition.
Poor sleep is a problem in adolescents and young adults. may be associated with changes in connectivityWithin this network. This is important because our brains still have a lot of development until late adolescence, or young adulthood.
A good quality and quantity of sleep can help us have more energy and better well-being.
This disruption could have knock-on effects on cognition such as interfering in concentration and memory-based processing as well as more advanced cognitive processing.
Alterations in sleep patterns and difficulty falling or staying asleep are important signs of the aging process. These sleep disturbances can be a contributing factor to cognitive decline in older adults and psychiatric disorders.
The right amount
Our study sought to better understand the relationship between sleep, cognition, and wellbeing. Insufficient and excessive sleep were associated with impaired cognitive performance in a population of middle-aged to elderly adults. This included nearly 500,000 adults. UK BioBank. We did not study adolescents and children, so their sleep requirements may be different.
Our main finding was that seven hours of sleep per day was the optimal amount. More or less sleep has less benefits for mental health and cognition. In fact, we found that people who slept that amount performed – on average – better on cognitive tests (including on processing speed, visual attention and memory) than those who slept less or more. Individuals need seven hours of uninterrupted sleep every night without too much fluctuation.
However, everyone responds differently to sleep deprivation. Genetics and brain structure were key factors in the relationship between sleep duration, cognition, and mental health. We noted that the brain regions that are the most affected by sleep deprivation include the hippocampus, well known for it’s role in learning and memory, and areas of the frontal cortex, involved in top-down control of emotion.
However, sleep may have an effect on our brains. It could also work the opposite way. It could be that the age-related shrinkage and loss of brain regions that regulate sleep and wakefulness can lead to sleep problems later in life. It may lead to a decrease in production secretion of melatoninOlder adults have lower levels of, a hormone that regulates the sleep cycle. This finding seems to support evidence that there is additional evidence. is a link between sleep duration and the risk of developing Alzheimer’s disease and dementia.
Our study shows that seven hours of sleep is the best for dementia prevention. However, adequate sleep can help with memory protection and symptoms. This highlights the importance to monitor sleep duration in older patients suffering from psychiatric disorders or dementia in order for them to improve their cognitive functioning, mental well-being, and overall health.
How to improve your sleeping habits
What can we do to improve our sleeping habits and our overall wellbeing?
A good start is ensuring that the temperature and ventilation in your bedroom is good – it should be cool and airy. Avoid drinking alcohol before you go to bed. You should be relaxed and calm when you try to fall asleep. For many people, it is helpful to think of something pleasant and relaxing, like the last time you went to the beach.
Technological solutionsWearable devices and apps can also be helpful for mental health.
To live a happy life and be able to function at your best, you will need to monitor your sleep patterns to make sure you are getting seven hours a night.
Barbara Jacquelyn Sahakian is professor of clinical neuropsychology at the University of Cambridge; Christelle Langley is a postdoctoral research associate in cognitive neuroscience at the University of Cambridge; Jianfeng Feng is professor of science and technology for brain-inspired intelligence at Fudan University, China; and Wei Cheng is a young principal investigator of neuroscience at Fudan University, China.
This article is republished under Creative Commons license from The Conversation. You can read the original article.
Main image: Tania Mousinho