SUMMARY: There are strong relationships between sleep problems and mental illness. The research confirms that if you have one, your chances of having the other increase. In fact, people with mental health issues are more likely to have sleep problems than those without mental health issues.

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 Originally published November 2017. Updated and expanded, April 17, 2019.

The Relationship Between Sleep, Mood and Gut Bacteria

As a busy mom of three, I know that getting enough good quality sleep is so important. After one night of bad sleep because of a sick kid or when I injured ankle and I had to sleep with it propped up, I’m a wreck. I can’t think, I can’t focus and my mood is all over the place. I can’t remember how I use to function when I had three little ones getting me up in the night, or before that how I use to stay up past midnight doing homework or talking with friends.

Over the last couple of years, I’ve become more attuned to how much sleep my body needs and what I can do to get sleep. I know that getting enough sleep, and not too much, is essential to supporting my mental wellness. There are strong relationships between sleep problems and mental illness. The research confirms that if you have one, your chances of having the other increase.

People with mental health issues are more likely to have sleep problems than those without mental health issues. Studies have found that between 65 and 90% of adults with depression and 50% of adults with anxiety also have sleep issues. Another study found that people with insomnia were four times as likely to develop depression than those without insomnia. People with insomnia were also more likely to have anxiety. And, this is the worst part, people with sleep issues are less likely to respond treatment for depression and PTSD and are more likely to suffer from a return of depressive symptoms. 

There are strong relationships between sleep problems and mental illness. The research confirms that if you have one, your chances of having the other increase. Click To Tweet


Circadian Rhythms

You may have heard circadian rhythms. These are patterns of brainwave activity, hormones, cell regeneration and biological activities that occur on a daily basis. For example, our kidneys slow down at night so we wake up less often to use the bathroom. Digestion also slows down at night.

Sleeping well at the right time each day is essential to keeping the circadian rhythms functioning properly. And when our bodies are function properly, we feel better all around.

The fact that our microbes are actually the regulators of this function and that our sleeps patterns are an issue for our microbes should not surprise us – well, if you’ve been reading my blog for a while you won’t be surprise that the gut biome is related to pretty much everything in the body especially mental and brain health. Our microbes need us to rest so they can do their thing while we sleep and keep their balance.

So what should you do? Should you work on sleeping better to help the microbes or should you work on your gut health to help you sleep better? The answer is to do both. There are number of strategies that can help.

Circadian Rhythms, Sleep and Stress

Cortisol is one hormone which is part of your circadian rhythms. Under normal (non-stressed) conditions, cortisol levels would increase before waking, and slowly drop during the day.  And this pattern makes sense, because we know that cortisol helps increase mental clarity as well as blood sugar to fuel your muscles. Both mental clarity and fuel for our muscles are most important when we are awake.

But we also need the effect of the cortisol to “wear off” by the end of the day so we can start getting tired and relaxed enough to get a good night’s sleep. In other words, in the evenings, we want to focus resting and digesting. But, when we are under stress, our cortisol levels stay higher and may not decrease enough in the evening to support good sleep. High levels of cortisol can interfere with learning and memory, and elevated levels of cortisol are linked to mental illness (including depression) and lower levels of resilience in adolescents.

Reset Your Circadian Rhythm

To help reset your circadian rhythm:

  • Go to bed at a set time and get up at the same time as much as possible – this means not sleeping in too late on the weekends
  • Avoid bright lights near bedtime
  • Avoid eating or exercising close to bedtime
  • Sleep in dark space – too much light tricks the body into thinking it is time to be awake
  • Develop a relaxing routine before bed whether it is taking a bed, deep breathing exercises or having a nice cup of herbal tea such as chamomile or valerian.
  • For those who have irregular work and therefore, sleep schedules, consider talking to a practitioner about taking melatonin.




Support Your Gut

Diet also plays a role in the relationship between sleep and the gut biome. In a study with mice, both high fat and low fat diets played a negative role in the function of circadian rhythms and they also altered the microbiome. In both cases, short-chain fatty acid production was lower, especially butyrate which is essential for circadian rhythm function. Butyrate is produced by beneficial colon bacteria from resistant starch found in complex carbohydrates such as potatoes, wheat, rice, legumes and sweet potatoes.

To improve gut health:

  • Eat prebiotic foods that feed gut bacteria like asparagus, green bananas (they only need to be slightly green), onions and garlic, beans and legumes, artichokes and apples.
  • Eat foods with resistant starch like oats, rice, beans and legumes, green bananas, potatoes and sweet potatoes.
  • Take probiotics that can help melatonin levels which can, in turn, help restore circadian rhythms.
  • Butyrate supplements are available if you are unsure as to how well you are producing it.

Sleep is one more example of the potential problems caused by dysbiosis that can effect our mental health. This relationship provides another reason why we should be focused on improving our gut health so we can have more energy and feel better. 


Reduce Stress

I’d love to help you manage your stress better so that you can reduce your cortisol levels, reset your circadian rhythms, and support your gut health.  And you can do all three at once by reducing stress! There are really two main strategies to go about reducing your stress.

First off, you can reduce the amount of stress put on you by re-balancing some demands. Try:

  • Saying “no”;
  • Getting more support;
  • Delegating to someone else;
  • Re-negotiating deadlines that seem unreasonable;
  • When working, focus on just one thing at a time (don’t multi-task).

Secondly, since you can’t (and maybe don’t want to) completely remove stress from you life, you want to learn to deal with it better. You can improve your personal stress tolerance by trying to:

  • Have some fun and laugh;
  • Make time for people (and pets) you love;
  • Be mindful and live more “in the moment”;
  • Have one or two cups of green tea (which has been shown to lower stress levels);
  • Do light exercise most days per week (e.g. yoga, swimming, or tai chi);
  • Go for a walk outside and generally spend more time in nature;
  • Eat a nutrient-rich diet;
  • Meditate or deep breathing;
  • Relax every evening (e.g. have a bath or read a book);
  • Listen to soothing music;
  • Do a “brain dump” every night before bed where you just make notes of things you’re keeping track of in your head so you can relax more;
  • Treat yourself to a massage, nice meal, or pedicure.

If you can reduce your stress, reset your circadian rhythms and get more sleep, your gut bacteria will thank you!


Bergland, C.  (2013). Cortisol: Why the “Stress Hormone” Is Public Enemy No. 1.

Circadian Disorganization Alters Intestinal Microbiota, Robin M. Voigt,1 et al, PLoS One. 2014; 9(5): e97500.

Effects of diurnal variation of gut microbes and high-fat feeding on host circadian clock function and metabolism. Leone V1, et al, Cell Host Microbe. 2015 May 13;17(5):681-9.

Melatonin regulation as a possible mechanism for probiotic (VSL#3) in irritable bowel syndrome: a randomized double-blinded placebo study, Wong RK1 et al, Dig Dis Sci. 2015 Jan;60(1):186-94.

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Kolbe, I., Dumbell, R. & Oster, H. (2015). Circadian Clocks and the Interaction between Stress Axis and Adipose Function. Int J Endocrinol. 2015:693204. doi: 10.1155/2015/693204. LINK:

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