According to researchers from the University of Cambridge and Fudan University, seven hours are the ideal amount of sleep for people in their mid-winter hours, with too little or too much sleep associated with poorer cognitive performance and mental health.
Sleep plays an important role in enhancing cognitive function and maintaining good psychological health. It also helps maintain the brain''s health by eliminating waste goods. We often notice changes in our sleeping patterns, including difficulty falling asleep and staying asleep, as well as decreased quantity and quality of sleep.
Researchers from the United Kingdom and China conducted a series of cognitive tests for nearly 500,000 adults aged 38-73 years old. Participants were asked about their sleeping patterns, mental health, and wellbeing, and took part in a series of cognitive tests. Nearly 40,000 researchers were involved in brain imaging and genetic data.
Combining these findings, the team concluded that both inadequate and excessive sleep duration were linked to impaired cognitive performance, such as processing speed, visual attention, memory, and problem-solving skills. Seven hours of sleep per night was the best amount of sleep for cognitive performance, but also for good mental health, with individuals experiencing more symptoms of anxiety and depression and worse overall wellbeing if they reported sleeping for longer or shorter periods.
One possibility for the connection between insufficient sleep and cognitive decline is the absence of slow-wave deep sleep. This type of sleep has been shown to be in close proximity to memory consolidation as well as the build-up of amyloid, a key protein, which, when it misfolds, can cause tangles in the brain characteristic of some forms of dementia. Furthermore, lack of sleep may hinder the brain''s ability to rid itself of harmful chemicals.
The researchers also discovered a link between the amount of sleep and the structure of brain regions involved in cognitive processing and memory, once more, with greater fluctuations associated with more than or less than seven hours of sleep.
One thing that was important to cognitive performance and good mental health and wellbeing was achieving a consistent seven-hour sleep each night, without too much variation in duration. Previous studies have also shown that decreased inflammation is linked to an increase in susceptibility to age-related illnesses in elderly people.
According to Professor Jianfeng Feng from Fudan University in China, too little or too much sleep can cause cognitive problems. However, our analysis of individuals over a longer period of time appears to confirm this assumption. However, the reasons why older people have poorer sleep are fairly complex, driven by a combination of our genetic makeup and the structure of our brains.
According to the researchers, inadequate or excessive sleep duration might be a risk factor for cognitive decline in ageing. This is supported by previous research that found a link between sleep duration and the risk of developing Alzheimers disease and dementia, in which cognitive decline is a hallmark symptom.
One of the researchers at the University of Cambridge, Professor Barbara Sahakian, said that staying well nights sleep is crucial at all stages of life, but particularly as we age. Having the capacity to maintain good mental health and wellbeing, as well as avoiding cognitive decline, is critical to maintaining good mental health and wellbeing.
The research was supported by the Shanghai Municipal Science and Technology Major Project, the Shanghai Center for Brain Science and Brain-Inspired Technology, the 111 Project, the National Natural Science Foundation of China, and the Shanghai Rising Star Program.