We’re constantly being reminded by news articles and social media posts that we should be getting more sleep – not sleeping enough is bad for our brain, heart and overall health, not to mention our skin and sex drive – but what about sleeping “too much”?
Recent reports that sleeping more than nine hours could be worse for our health than sleeping too little may be confusing, write experts Charlotte Gupta and Gabrielle Rigney in The Conversation, who unpack the evidence of how much sleep we actually need, and how sleeping a lot can affect our health.
Essential for health
Along with nutrition and physical activity, sleep is an essential pillar of health.
During sleep, physiological processes occur that allow our bodies to function effectively when we are awake – including those involved in muscle recovery, memory consolidation and emotional regulation.
The Sleep Health Foundation, Australia’s leading not-for-profit organisation that provides evidence-based information on sleep health, recommends adults get seven to nine hours of sleep per night.
Some people are naturally short sleepers and can function well with less than seven hours.
However, for most of us, sleeping less than seven hours will have negative effects. These may be short term; for example, the day after a poor night’s sleep we might have less energy, worse mood, feel more stressed and find it harder to concentrate at work.
In the long term, not getting enough good quality sleep is a major risk factor for health problems. It’s linked to a higher risk of developing cardiovascular disease – such as heart attacks and stroke – metabolic disorders, including type 2 diabetes, poor mental health, like depression and anxiety, cancer and death.
So, it’s clear that not getting enough sleep is bad for us. But what about too much sleep?
Could too much sleep be bad?
In a recent study, researchers reviewed the results of 79 other studies that followed people for at least one year and measured how sleep duration affects the risk of poor health or dying to see if there was an overall trend.
They found people who slept for short durations – less than seven hours a night – had a 14% higher risk of dying in the study period, compared with those who slept between seven and eight hours. This is not surprising, given the established health risks of poor sleep.
However, the researchers also found those who slept a lot, which they defined as more than nine hours a night, had a greater risk of dying: 34% higher than people who slept seven to eight hours.
This supports similar research from 2018 which combined results from 74 previous studies that followed the sleep and health of participants across time, ranging from one to 30 years. It found sleeping more than nine hours was associated with a 14% increased risk of dying in the study period.
Research has also shown sleeping too long (meaning more than required for your age) is linked to health problems such as depression, chronic pain, weight gain and metabolic disorders.
This may sound alarming. But it’s crucial to remember these studies have only found a link between sleeping too long and poor health: this doesn’t mean sleeping too long is the cause of health problems or death.
So, what’s the link?
Multiple factors may influence the relationship between sleeping a lot and having poor health. It’s common for people with chronic health problems to consistently sleep for long periods. Their bodies may need additional rest to support recovery, or they may spend more time in bed due to symptoms or medication side effects.
People with chronic health problems may also not be getting high quality sleep, and may stay in bed for longer to try to get some extra sleep.
Additionally, we know risk factors for poor health, such as smoking and being overweight, are also associated with poor sleep.
This means people may be sleeping more because of existing health problems or lifestyle behaviours, not that sleeping more is causing the poor health.
Put simply, sleeping may be a symptom of poor health, not the cause.
What’s the ideal amount?
The reasons some people sleep a little and others sleep a lot depend on individual differences, and we don’t yet fully understand these.
Our sleep needs can be related to age. Teenagers often want to sleep more and may physically need to, with sleep recommendations for teens being slightly higher than adults at eight to 10 hours. Teens may also go to bed and wake up later.
Older adults may want to spend more time in bed. However, unless they have a sleep disorder, the amount they need to sleep will be the same as when they were younger.
But most adults will require seven to nine hours, so this is the healthy window to aim for.
It’s not just about how much sleep we get. Good quality sleep and a consistent bed time and wake time are just as important – if not more so – for overall health.
The bottom line
Given many adults are not receiving the recommended amount of sleep, we should focus on how to make sure we get enough sleep, rather than worrying we are getting too much.
For the best chance of a good night’s sleep, people need to get sunlight and stay active during the day, and try to keep a regular sleep and wake time. In the hour before bed, it’s best to avoid screens, do something relaxing, and make sure our sleep space is quiet, dark and comfortable.
If they notice they are regularly sleeping much longer than usual, it could be their body’s way of saying something else is going on.
Charlotte Gupta – Senior Postdoctoral Research Fellow, Appleton Institute, HealthWise Research Group, CQUniversity Australia.
Gabrielle Rigney – Senior Lecturer in Psychology, Appleton Institute, CQUniversity Australia.
See more from MedicalBrief archives:
Too little or too much sleep bad for heart health
Not enough night-time sleep linked to clogged arteries – Swedish study
Sleep duration’s effect on elevated heart risk — ACC:2021
How you sleep could be ‘strongest predictor’ of when you will die – US study
Seven hours is ideal amount of sleep in middle-age and older – UK-China study