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How does sleep affect diabetes?

Jed Campbell-Williams
Health Adviser Team Manager at Bupa UK
23 June 2022
Next review due June 2025

If you have type 2 diabetes, you might think about changing your diet and exercise routine to improve your blood sugar levels. And this can definitely help. But did you know that good quality sleep can affect your blood sugar levels too? Here I’ll explore the connection between how well you sleep at night and your risk of diabetes.

How does sleep affect my blood sugar levels?

Sleep affects many areas of your health and wellbeing. It can alter everything from your mental health to your immune system. But one area it can have a surprising impact on is your blood sugar levels. When you sleep well, your body lowers your blood sugar levels as you rest. This may be due to:

  • sleep reducing your cortisol levels. Cortisol is a stress hormone that can increase your blood sugar levels if you have too much of it.
  • fewer inflammatory chemicals in your body. Some of these chemicals are linked to insulin resistance. Insulin resistance happens when your pancreas no longer produces enough of the hormone insulin. This can cause high blood sugar levels.
  • your body clock. Your blood sugar levels reduce more when you sleep at night-time than during the daytime. This is why shift workers can sometimes struggle with high blood sugar levels.

High blood sugar levels can reduce sleep quality too

If you have diabetes, you are less likely to sleep well. This can make managing your blood sugar levels even harder. You may also struggle to sleep if you have prediabetes as well as type 2 diabetes. It is not clear why your sleep might be affected if you have these conditions but taking steps to improve your sleep quality may help.

How can I sleep better?

Your blood sugar levels might be higher than usual after just one night of poor sleep. We all have a sleepless night every now and again, but it is more important to take action if you don’t often sleep well.

Studies show you need to sleep for more than 4 hours, to improve your blood sugar levels, with the ideal amount being between 7-9 hours. You also need to sleep deeply enough to get to the so-called ‘slow wave’ stage of sleep. Ideally, you will sleep during the night too, instead of relying on daytime napping.

You can take steps to improve your sleep by:

  • getting up at the same time every morning, including at the weekends. This can help to regulate your body clock so that you sleep better the following evening
  • avoiding screen time in the evening, which can raise your stress hormone cortisol. This in turn can increase your blood sugar levels
  • exercising – ideally in the morning. Morning exercise can help to regulate your body’s internal clock. This reduces your risk of both diabetes and cardiovascular disease
  • taking time out to relax during the day, which can also help to prepare your body for deeper sleep at night

What else can I do to manage type 2 diabetes?

Sleep alone is not enough to manage your blood sugar levels. You also need to eat a healthy, balanced diet that is low in added sugars and focuses on wholegrains, proteins and vegetables. In addition, resistance exercise, such as planks and squats, can improve insulin sensitivity.

Reducing stress is also important, as this could lower your cortisol levels and improve your blood sugar levels. So, try to find time each day to read, practice yoga, or do something you find relaxing.

Lifestyle changes can make a big difference in managing type 2 diabetes and prediabetes. But you should still see a doctor regularly to make sure your blood sugar levels are well managed.


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Jed Campbell-Williams
Jed Campbell-Williams
Health Adviser Team Manager at Bupa UK

    • Sleep and blood glucose levels. The Sleep Foundation. www.sleepfoundation.org, updated April 2022
    • Mental health. The Sleep Foundation. www.sleepfoundation.org, updated April 2022
    • Sleep and the immune system. The Sleep Foundation. www.sleepfoundation.org, updated April 2022
    • Insulin resistance. Diabetes UK. www.diabetes.co.uk, accessed 22 June 2022
    • Reutrakul S, Hood M, Crowley M et al. Chronotype is independently associated with glycaemic control in type 2 diabetes. Diabetes care 2013;36(9):2523-9. doi: 10.2337/dc12-2697
    • Shift work and blood sugar. Diabetes UK. www.diabetes.co.uk, accessed 22 June 2022
    • Donga E, Dijk M, Dijk J et al. A single night of partial sleep deprivation induces insulin resistance in multiple metabolic pathways in healthy subjects. J Clin Endocrinol Metab 2010: 2963-8. doi: 10.1210/jc.2009-2430
    • How much sleep do we really need? The Sleep Foundation. www.sleepfoundation.org, updated April 2022
    • Tasali E, Leproult R, Ehrmann D et al. Slow-wave sleep and the rise of type 2 diabetes in humans. Proc Natl Aca Sci USA 2008;105:1044-9. doi: 10.1073/pnas.0706446105
    • Healthy sleep tips. The Sleep Foundation. www.sleepfoundation.org, updated April 2022
    • What is a healthy balanced diet? Diabetes UK. www.diabetes.org.uk, accessed 22 June 2022
    • Strasser B and Pesta D. Resistance training for diabetes prevention and therapy. Biomed Res Int 2013: 805217. doi: 10.1155/2013/805217
    • Guide to diabetes – stress. Diabetes UK. www.diabetes.org.uk, accessed 22 June 2022
    • Lifestyle changes for type 2 diabetes. Diabetes UK. www.diabetes.co.uk, accessed 22 June 2022
    • Hower I, Harper S and Buford T. Circadian rhythms, exercise and cardiovascular health. J Circadian rhythms 2018;16:7. doi: 10.5334/jcr.164

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