How do sleep and the gut interact? How can sleep help achieve a healthy gut?
Sleep impacts on many aspects of physical and mental health. If you’re not sleeping well or not getting enough sleep, it’s hard to maintain good health and feel well. Sleep can impact on gut health, so ensuring you’re getting enough sleep and have good quality sleep, is an important part of achieving a healthy gut.
There are a range of ways that sleep can impact on gut health, but 3 areas to understand and pay attention to are:
- Circadian (body-clock) regulation of sleep, wake and gastrointestinal function
- The effect of inadequate sleep on metabolism and dietary choices
- The impact of sleep disorders on eating habits, metabolism and gastrointestinal symptoms
1. The circadian rhythm (body clock)
“Rhythm is something you either have or don’t have, but when you have it, you have it all over.”
Elvis Presley 1935-1977
All body functions come under the control of our internal clock, called the circadian rhythm. There is a master clock in the brain, but every organ and cell in the body also contains their own clocks. When these peripheral clocks are in sync with the central master clock, we feel well and health is usually optimal. However, there are many situations when these clocks get out of sync and health suffers.
What has timing of sleep and eating got to do with it?
Regulating sleep is one of the important functions of the circadian master clock but appetite and energy regulation also come under circadian control. In essence, there are periods during the day when our gut is more geared up to receive food and break it down, and other times where waste is moved through the large bowel. If we eat meals irregularly, we end up taking in food at times when the body is not ready to deal with it. This can lead to symptoms of nausea or bloating. Giving irregular signals to the peripheral clocks in the gut by eating at irregular times, can also lead to the clocks in the gut being out of sync with the master clock in the brain. This can result in situations where the appetite centres in the brain trigger hunger signals whilst the gut is not ready to receive or metabolise food.
In addition to impacting on gut motility, the circadian system controls how we handle energy. There have been numerous experiments showing irregular eating leads to weight gain and this data is starting to be replicated in real-world studies. If we eat meals irregularly, we end up taking in calories at times when the body is not ready to deal with it and can deal with it inappropriately leading to higher glucose levels and greater storage of energy and weight gain.
Eating during set times rather than grazing
Research discussed in the New York Times Magazine, and published in Cell Metabolism looked at the role of eating outside a set 9 or 12 hour window each day. Researchers found that if they allowed mice to eat only within a 9 or 12 hour window each day (time restricted feeding), they remained lean and healthy even when eating an unhealthy diet. Mice that were allowed to eat whenever they wanted, gained weight even when eating a healthy diet. These changes were there even though both groups ate the same amount of calories. In modern society, where we eat on the run, graze, and rarely stop for set meal times, yet struggle with weight control this research provides important insights. With our increasingly busy schedules and irregular patterns this may be one of the important factors in the obesity epidemic.
- Eat breakfast – It’s the best meal to get you set up for a great day. Breakfast alerts our body that it is the start of the day.
- Eat regular meals – Regular meal times and predictable portion sizes help synchronise our peripheral clocks with the central mask clock and ensure gastrointestinal function is well regulated and in sync.
- Keep eating to within a 12 hour window – Research shows that grazing across the day, eating outside a 12 hour window, leads to greater weight gain.
2. Not getting enough sleep
There has been lots of data in recent years showing that if we are not getting enough sleep it changes the way we take in energy and what type of calories we crave.
Shorter sleep leads to taking more calories
People who sleep for shorter periods have been shown to take 500 more calories per 24 hours than those who are well rested. They also to take in more carbohydrates, choosing salty, starchy foods rather than protein-based food. In addition to taking in more calories, those calories are more efficiently stored due to changes in metabolism, resulting in greater weight gain compared to those who are well rested. The increase in sympathetic nervous system activity that is part of sleep deprivation is one of the mechanisms of changes in metabolism. It results in mobilisation of glucose stores, resulting in higher glucose blood levels which in turn increases the risk of diabetes and cardiovascular disease.
- Prioritise sleep – Make enough time for sleep and winding down before bed is the key to ensuring you’re not running short on sleep
- Embrace napping – If you’re busy and feel you’re running short on sleep, don’t feel guilty about napping. Catching a nap when the opportunity arises can be a great way of catching up on sleep.
3. Sleep disorders can impact on gut health
One in 20 people with insomnia have compulsive eating during sleep. People with sleep apnea, gain on average 10kg in the year before they are diagnosed. Shift workers have an increased risk of obesity. Why does this occur and how do sleep disorders, metabolism and the gut interact?
Disrupted sleep leads to disrupted gut function
Many people I see with sleep disorders, such as insomnia, sleep apnea or disturbed sleep from other conditions such as fibromyalgia, describe gastrointestinal symptoms such as bloating or irregular bowel movements. When sleep is disrupted, it impacts on regulation of a range of other body functions such as the gut.
When we are sleeping, the gut, like other body organs, should be relatively quiet, with minimal motility. Contrast this with what happens when we are awake, when the gut needs to be active, moving what we have eaten through the intestines, absorbing nutrients and fluid. But when sleep is frequently disrupted, as happens with sleep apnea or insomnia, the gut can behave like it’s awake through the night which can cause a range of symptoms including abdominal discomfort.
- Diagnose and manage sleep disorders – If your sleep is disrupted and you think you might have a sleep disorder like insomnia or sleep apnea, talk to your health professional.
- What is the circadian rhythm?
- Having trouble sleeping? When is it insomnia?
- Supercharged food – Great recipes and resources for a healthy gut
Need more information about how you can sleep better?
At Sleephub we understand the struggle people endure with sleeping problems which is why we have created a FAQs page with information for those seeking information about sleep disorders and potential solutions.