This Is the Perfect Amount of Sleep Once You Hit Middle Age

If you've been skimping a bit on sleep and breaching that long-held "eight hours a night" mantra, you might be OK—as long as it's only by an hour or so, and you're a Gen Xer or boomer. Scientists in the UK and China have found that seven hours is actually the new magic number for those in middle age or older, with people getting in less than or more than that at risk of losing focus and having more problems with cognitive tasks and decision-making, reports CNN. On the flip side, per the new research published in the Nature Aging journal, those in that age bracket who do get their seven hours in could avoid many of those issues, as well as give their mental health a boost.

Per data from a long-haul UK government study, the nearly half-million subjects, ages 38 to 73, were questioned on their mental health and well-being, as well as on their sleep patterns, and were also given a series of cognitive tests. Scientists also had brain imaging and genetic data for about 8% of the participants. The researchers found that those who got less than seven hours of shut-eye (or exceeded that) had trouble paying attention, experienced memory problems, and saw a slowdown in processing speed, per ScienceDaily. Those two groups also suffered more symptoms of anxiety and depression than those who snored away for seven hours, and reported a decline in their overall well-being.

Researchers believe that cognitive decline tied to too little sleep may be due to not getting enough "deep" sleep, which is when the body does most of its hard work in repairing from the previous day. They're not really sure why too much sleep would have similar effects. The scientists also note that while seven hours seems to be the sweet spot for many, those in the real world shouldn't necessarily fret if they're not right at that level. "Sleep is like shoe size—one size does not fit all, and ... classifying 'good sleep' in this way can cause confusion and anxiety for many," Russell Foster, who heads up the Sir Jules Thorn Sleep and Circadian Neuroscience Institute and wasn't involved in the study, tells CNN. He notes everyone has different sleep patterns based on various factors, including individual health status, and you may fare just fine even if not adhering too closely to the seven-hour mark. (More sleep stories.)