You may be sleeping more than you need – so what’s the magic number?

Many of us aim for the often-quoted ‘eight hours of sleep’ a night to stay sharp in the day. But new research suggests we may not need as much as this.

If you are becoming a little too reliant on your morning expresso to start your day, you might want to reconsider how much shuteye you are getting.

While many of us believe eight hours of slumber is the goal, UK research suggests seven hours of sleep is optimal.

What does the research say?

The University of Cambridge study, involving 500,000 men and women aged between 38 and 73, found if you are middle-aged or older, you should be aiming to get around seven hours’ sleep every night to keep your brain sharp.

The study found too little or too much sleep can impact important brain structure and may contribute to cognitive decline and even psychiatric disorders as we get older.

Why seven hours’ sleep is best

“People who slept for seven hours had the best cognition and wellbeing and fewer mental health symptoms, compared with people who slept six hours or less, or eight hours or more,” study author Professor Barbara Sahakian says.

Prof Sahakian says sleep is an important part of maintaining normal brain functioning.

“During sleep we consolidate our memories so that what we learn during the day, including our experiences, can be remembered and retrieved when needed in the future,” she says.

“Importantly, toxins are also cleared from our brain during sleep.”

Sleep Health Foundation chief executive Dr Moira Junge says aiming for about seven hours sleep a night is a good target, while noting some people may need slightly more or less.

“Some nights we might get a little less or a little more,” Dr Junge says.

“Aiming for around seven hours a night is a good goal but people shouldn’t stress about getting exactly seven hours.

“Adults need around seven to nine hours of sleep for mental and physical wellbeing.”

The problem with not enough sleep

Prof Sahakian says sleep deprivation affects the parts of the brain that play key roles in learning, memory and emotion.

Research shows a fatigued person is more likely to have decreased cognitive performance and increased mood disorders.

The problem with too much sleep

Oversleeping has been associated with health problems like type 2 diabetes, heart disease, obesity, depression and headaches, but Dr Junge says it’s unclear whether sleep causes these problems or vice versa.

“If you are so sleepy that you need more than 10 hours sleep, it is possible there is something else going on with your health and it’s that issue that is causing you to sleep so much,” she says.

How to get the right amount of sleep

Dr Junge says there are some strategies to help achieve a good bedtime routine, such as:

  • Try to go to bed at the same time each night
  • Turning off screens one or two hours before bed
  • Avoiding caffeine, alcohol and cigarettes two or three hours before bed
  • Winding down before bedtime
  • Ensuring the bedroom is quiet, dark and a comfortable temperature

Written by Sarah Marinos.