This workout is 'just as good' as a 90-minute nap for preserving memory and boosting brain health, a new study finds

It's thought that almost half of women in Britain don't get enough sleep and don't feel well-rested when they wake up, yet rest is one of the most important ways to keep your brain healthy and form new memories. How do you make sure that happens when you can't sleep through the night?

A new study from McGill University has the answer. They found that 20 minutes of moderate-to-vigorous exercise had the same benefit for brain health as having a 90-minute nap. Both helped participants retain short- and long-term memory.

Researchers assigned participants a 90-minute nap or 20 minutes of moderate-to-vigorous exercise after 30 hours without sleep. After the intervention, they gave them an image memory test. Three days later, those who had exercised or napped did 22 per cent better on the memory test than those who did neither.

Interestingly, the interventions helped in different ways. The nap appeared to help the brain recharge, making it easier to take in and retain new information, while the exercise helped the brain work more efficiently without added tiredness.

No one is suggesting that exercise can replace a good night's sleep. The researchers hope that the findings can help in workplaces where sleep loss is common, such as healthcare and emergency response. However, it's also a useful insight for those struggling to get a good night's sleep, whatever the reason.

“Sleep loss affects nearly every aspect of how we think and function, but many people can’t simply stop what they’re doing and get more sleep,” said senior author Marc Roig, Professor in McGill’s School of Physical and Occupational Therapy. “Our findings show that even a brief bout of exercise may help preserve one of our most important cognitive abilities.”

If you are experiencing insomnia, speak to your doctor.

What is moderate-to-vigorous activity?

To reap the benefits of exercise for brain health, you need to be doing it at the right intensity - not too hard or too easy. Moderate-to-vigorous-intensity exercise is about 80 per cent of your maximum heart rate (220 minus your age), and the study suggests doing this for 20 minutes.

"This heart rate has a distinct feel to it," says Michael Betts, a personal trainer for almost 40 years and the founder of TrainFitness. "You will be able to speak in short phrases, but you couldn't hold a conversation. If you can chat comfortably, you are below the level that the study used. If you cannot speak at all, dial it back."

It's particularly important to get the intensity right, as other research has found that gentle exercise for about the same duration does very little for brain health. "Repeatedly grinding through sessions while exhausted makes mood and reaction times worse. This was one short, properly hard effort, and that precision is the finding."

The type of exercise you do isn't important. You could do a quick walking workout, classic strength training, or go swimming and see the benefit. You can also keep an eye on your live heart rate with a fitness tracker, such as a Fitbit or Garmin watch.

"Do the twenty minutes before the part of your day that needs your brain, not after. In the study, people exercised and then learned," adds Michael.