Researchers have concluded that seven hours of sleep each night is the optimal amount for good mental health, well-being and cognitive performance for people in their late 30s to early 70s.
They reached their conclusions by looking at UK biobank data on nearly 500,000 adults.
In their new paper, the researchers wrote: “We identified a nonlinear association between sleep, with approximately seven ideal hours of sleep, genetic and cognitive factors, brain structure, and mental health as key criteria. Longitudinal analysis showed that both insufficient and excessive sleep duration were significantly associated with Cognition declines upon follow-up.
The team, led by neuroscientist Yuzhu Li from Fudan University in China, and psychiatry researcher Barbara Sahakian, from the University of Cambridge, looked at data from 498,277 participants aged 38 to 73 as part of the UK Biobank study.
About 48,500 participants also underwent neuroimaging, and nearly 157,000 participants completed a follow-up mental health questionnaire online. All of these data points came together to provide a fairly comprehensive view of how the amount of sleep people get relates to other aspects of their mental health.
Because of the neuroimaging data, the researchers were also able to look at whether there were structural or genetic brain mechanisms behind the U-shaped curve. Modeling by the researchers suggests that genes and brain structure play a role, but more research will be needed to follow these leads.
One of the researchers, Jianfeng Feng, from Fudan University, says: “While we cannot definitively say that too little or too much sleep causes cognitive problems, our analysis that looks at individuals over a longer period of time supports this notion. But the reasons why Older adults with poor sleep appear complex, influenced by a combination of genetics and the structure of our brains.”
So, with all this in mind, we need to mention a couple of caveats. This research is very broad, but it is still only an observational study, which only shows the associations that appear in the data.
Unfortunately, we cannot know if sleeping less or more than seven hours actually causes problems with mental health, well-being, or cognitive performance, or vice versa, whether these problems are causing people to sleep more or less.
And second, this study doesn’t say that six or eight hours of sleep will lead to major changes in your individual well-being. And there are many reasons why people can’t sleep seven hours each night – whether it’s stress, work, or simply needing to get up in the middle of the night to urinate.
Most importantly, if you only feel refreshed if you get eight hours of sleep each night, don’t try to get up an hour earlier and anticipate the health benefits.
This study is useful in showing that getting seven hours of sleep each night as we head into middle age and older is a worthy goal. But we shouldn’t beat ourselves up if we can’t get that much sleep as individuals, according to rt.
And if you’re struggling to get enough sleep, a nap can really help.