Why too much sleep can drain your brain power

. . . and it could also raise your risk of a heart attack and stroke

DID you enjoy an extra hour in bed last Sunday when the clocks went back? We’ve been repeatedly warned about the dangers of not getting enough sleep so, understandably, most of us would have seized the opportunity to get more shut-eye.

But new research suggests that trying to pack in more sleep can actually undermine our health.

There is no question that a good night’s sleep benefits our brains. We feel groggy and irritable if we have slept badly, and long-term sleep deprivation can lead to serious damage.

It is when we are in deep sleep that our memories are preserved — and when channels open in our brains, allowing fluid to gush through and clear away any waste products that have built up during the day.

So, you might imagine that people getting the most sleep must have the healthiest brains. But a recent study, from Washington University Sleep Medicine Center in the U.S. concluded that for older adults, too much sleep may be as bad for their brains as too little.

The researchers looked at 100 adults, average age 75, who had been taking part in a long-term study of their brains, which included doing things like repeated memory tests.

THEY were also given portable EEGs (electroencephalographs) which measured their brain waves to provide an accurate picture of how much they were sleeping.

They couldn’t rely on the participants telling them this, as previous EEG studies have shown we actually sleep around an hour less each night than we think we do. So if you think you’re getting seven hours a night, you are probably only really having about six. That’s because we often wake up during the night but don’t remember doing so.

The researchers then compared how long the volunteers were sleeping with their mental performance over the five years of the study.

The best results were seen in those getting 4.5 to 6.5 hours of EEG-measured sleep each night, the equivalent of between 5.5 and 7.5 hours of self-reported sleep. People getting more, or less, than those amounts showed the biggest declines in brain power.

This fits in with other major studies, such as one published in the Journal of the American

Heart Association in 2017, which compared people’s levels of self-reported sleep with their risk of developing heart disease and dying. The people who said they slept significantly less, or more, than seven hours had a higher risk of having a heart attack or stroke than those around the seven hour mark (which is roughly the amount most Brits say they normally get, although the advice is to have eight hours).

As to why sleeping more than average is linked to poor health, this may be partly because people who are already in ill health spend more time in bed, so it’s not the long sleep that is causing the poor health, but the other way round.

But the researchers from Washington University Sleep Medicine Center also suggest that spending more time in bed can be counterproductive because it leads to more fragmented, poor-quality sleep, which is bad for you.

In other words, if you really want to enjoy the full benefits of a good night’s sleep, you need quality rather than just quantity.

Ensuring you have more quality sleep might sound difficult, particularly if you are an insomniac (someone, for example, who wakes up a lot in the middle of the night and then struggles to get back to sleep, as I do). But one of the most simple, but effective, ways to achieve it is to restrict the hours you spend in bed. The trick with Sleep Restriction Therapy (SRT) is to teach your brain to associate ‘bed’ with ‘sleep’ and nothing else.

The idea is that for a short period of time you restrict your sleep by getting up at the same time every morning but going to bed later than normal.

So if you normally go to bed at 11pm and get up at 7am, then you might try going to bed at midnight, or even 1am, instead. This will increase your sleep drive, so the next night you will fall asleep faster and hopefully wake up less frequently. You do this for a week or two, until you have got back into the habit of falling asleep easily, then gradually increase the amount of time you spend in bed until you get enough quality sleep.

This will vary from person to person, but one of the best ways of telling if you are getting ‘enough’ is whether you feel sleepy and irritable during the day.

If you want to try SRT there are four things to bear in mind. 1. Do not cut your time in bed to less than five hours. 2. Stick to it rigorously. 3. Do not lie down, nap or snooze during the day. 4. Do not drive or use machinery if you experience serious daytime sleepiness.

There are more details about how to do SRT in my recent book, Fast Asleep.

Note: if you have serious insomnia then you might want to talk to your GP or get professional support from someone who is trained to deliver CBT-I (Cognitive Behavioural Therapy for insomnia).