The optimal duration of a night’s sleep at this age is exactly seven hours. This conclusion was made by scientists from two universities, after analyzing extensive statistical and medical data.
If you consistently sleep less or more than seven hours a night in middle and older age, this can negatively affect your mental health and intelligence, warn researchers from Cambridge (UK) and Fudan (PRC) universities, whose article in the journal Nature Aging.
The scientists analyzed data on about half a million people of European descent aged 38 to 73. All of them provided information about how much and how much they sleep, about their mental health and well-being, and also performed numerous cognitive tests. In addition, nearly 40 participants underwent brain scans and submitted their genetic data.
The analysis of the collected information showed that both lack and excess sleep are associated with cognitive impairments — a decrease in brain speed, a decrease in visual attention, a deterioration in memory and the ability to solve problems.
Seven hours is the ideal night’s sleep for both intelligence and mental health.
People who regularly got less or more sleep had more symptoms of anxiety and depression and felt worse than those who always slept exactly seven hours a night.
Scientists have suggested that one of the possible reasons underlying this effect may be a violation of the phase of the deepest, “slowest” sleep, which is associated with the appearance in the brain tissues of amyloid plaques characteristic of some forms of dementia. In addition, chronic lack of sleep interferes with the process of cleansing the brain of toxins. The researchers also found that deviations in one direction or another from the optimal seven hours of sleep a night is associated with changes in the brain structures responsible for memory and cognition.