Is sleeping a lot actually bad for your health? A sleep scientist explains

We’re constantly being reminded by news articles and social media posts that we should be getting more sleep. You probably don’t need to hear it again – not sleeping enough is bad for your brain^[1], heart^[2] and overall health^[3], not to mention your skin^[4] and sex drive^[5].

But what about sleeping “too much”? Recent reports^[6] that sleeping more than nine hours could be worse^[7] for your health than sleeping too little may have you throwing up your hands in despair.

It can be hard not to feel confused and worried. But how much sleep do we need? And what can sleeping a lot really tell us about our health? Let’s unpack the evidence.

Sleep is essential for our health

Along with nutrition and physical activity, sleep is an essential pillar of health.

During sleep, physiological processes^[8] occur that allow our bodies to function effectively when we are awake. These include processes involved in muscle recovery, memory consolidation and emotional regulation.

The Sleep Health Foundation^[9] – 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^[10] and can function well with less than seven hours.

However, for most of us, sleeping less than seven hours will have negative effects^[11]. These may be short term; for example, the day after a poor night’s sleep you 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^[12] for health problems. It’s linked to a higher risk of developing cardiovascular disease^[13] – such as heart attacks and stroke – metabolic disorders^[14], including type 2 diabetes, poor mental health^[15], such as depression and anxiety, cancer^[16] and death^[17].

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^[18], researchers reviewed the results of 79 other studies that followed people for at least one year and measured how sleep duration impacts 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 to 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^[19], 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^[20] 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.

Read more: If 'correlation doesn’t imply causation', how do scientists figure out why things happen?^[21]

So, what’s the link?

Multiple factors may influence the relationship between sleeping a lot and having poor health.

It’s common^[22] 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^[23], and may stay in bed for longer to try and get some extra sleep.

Additionally, we know risk factors^[24] 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^[25] – and we don’t yet fully understand these.

Our sleep needs can be related to age. Teenagers^[26] often want to sleep more and may physically need to, with sleep recommendations for teens being slightly higher than adults at eight to ten 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^[27] 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 you get. Good quality sleep and a consistent bed time and wake time are just as important – if not more so^[28] – for your overall health.

The bottom line

Given many Australian adults^[29] 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.

To give yourself the best chance of a good night’s sleep^[30], get sunlight and stay active during the day, and try to keep a regular sleep and wake time. In the hour before bed, avoid screens, do something relaxing, and make sure your sleep space is quiet, dark, and comfortable.

If you notice you are regularly sleeping much longer than usual, it could be your body’s way of telling you something else is going on. If you’re struggling with sleep or are concerned, speak with your GP. You can also explore the resources on the Sleep Health Foundation^[31] website.

References

1. ^{^} brain (www.theage.com.au)
2. ^{^} heart (www.medicalnewstoday.com)
3. ^{^} overall health (www.abc.net.au)
4. ^{^} skin (www.theage.com.au)
5. ^{^} sex drive (www.abc.net.au)
6. ^{^} Recent reports (www.theage.com.au)
7. ^{^} could be worse (www.telegraph.co.uk)
8. ^{^} physiological processes (doi.org)
9. ^{^} Sleep Health Foundation (www.sleephealthfoundation.org.au)
10. ^{^} short sleepers (theconversation.com)
11. ^{^} negative effects (doi.org)
12. ^{^} major risk factor (jcsm.aasm.org)
13. ^{^} cardiovascular disease (jcsm.aasm.org)
14. ^{^} metabolic disorders (onlinelibrary.wiley.com)
15. ^{^} mental health (www.thelancet.com)
16. ^{^} cancer (jcsm.aasm.org)
17. ^{^} death (academic.oup.com)
18. ^{^} recent study (doi.org)
19. ^{^} 2018 (doi.org)
20. ^{^} health problems (doi.org)
21. ^{^} If 'correlation doesn’t imply causation', how do scientists figure out why things happen? (theconversation.com)
22. ^{^} common (pubmed.ncbi.nlm.nih.gov)
23. ^{^} high quality sleep (doi.org)
24. ^{^} risk factors (pubmed.ncbi.nlm.nih.gov)
25. ^{^} individual differences (www.sleephealthfoundation.org.au)
26. ^{^} Teenagers (www.sleephealthfoundation.org.au)
27. ^{^} will be the same (www.sleephealthfoundation.org.au)
28. ^{^} if not more so (www.sciencedirect.com)
29. ^{^} many Australian adults (doi.org)
30. ^{^} good night’s sleep (www.sleephealthfoundation.org.au)
31. ^{^} Sleep Health Foundation (www.sleephealthfoundation.org.au)