How Sleep Affects Digestion

We often think about digestion in terms of what we eat, but many other factors influence our gut function including our sleep. Quality sleep and digestive health are intertwined, and disturbances in one can quickly affect the other. Read on to explore how sleep affects digestion, why this connection is important, and how you can enhance both with simple lifestyle adjustments.

The Sleep-Digestion Connection

Our bodies run on circadian rhythms which are internal clocks that regulate the sleep-wake cycle, hormone release, body temperature, metabolism and cognitive function. This is important to help maintain good health. During sleep, the body is meant to repair and regenerate, including the gut lining and digestive tract. Poor sleep can interfere with this process, which may lead to:

• Sluggish digestion: Lack of sleep can affect our gastrointestinal motility, due to a disruption in circadian rhythms. When our sleep and digestion are optimal, digestive processes will slow down at night. However, when sleep is disrupted regularly, it may impact gut motility, leading to issues like constipation.

• Intestinal Permeability: Sleep deprivation can lead to an increase in cortisol levels. When cortisol levels are chronically elevated this can affect the function of tight junctions or ‘gates’ of the gut lining which help to keep out larger molecules like undigested food, toxins, and bacteria from passing into the bloodstream. When this occurs it is known as intestinal permeability or ‘leaky’ gut.

• Increased acid production: Some studies have suggested that people who experience gastroesophageal reflux disease (GORD) have reduced melatonin compared to individuals who don’t experience GORD. Melatonin is important in sleep regulation and may also influence gastric function. There is a suggestion that melatonin improves the tone of the lower oesophageal sphincter and can also help inhibit excretion of gastric acid both of which are important to protect against GORD.

• Hormonal imbalance: In addition to cortisol and melatonin, lack of sleep can also affect the hormones ghrelin and leptin, which regulate appetite. This imbalance can lead to overeating or cravings for high-fat, high-sugar foods due to lack of energy and tiredness, which can impact overall health.

• Altered microbiome: Chronic sleep deprivation can affect the balance of the microbiome. This may lead to inflammation of the GI tract and potential for GI problems including IBS and other digestive issues.

Good Sleep Hygiene for Better Digestion

Improving your sleep hygiene can have a positive impact on digestion. Here are a few tips to try:

• Stick to a Regular Schedule: Going to bed and waking up at the same time each day, even on weekends, can help improve your sleep as it helps regulate your circadian rhythm, positively affecting sleep and digestion. Waking up time is more important when it comes to your circadian rhythm so even if you don’t go to bed at the same time try waking up at within 15 minutes of the same time every day.

• Avoid Sleeping in: If you are feeling tired or feel the need to catch up on sleep it is better if you can to take a short afternoon nap of 30 mins rather than sleeping in, to keep your circadian rhythm working optimally.

• Avoid Heavy Meals Before Bed: Try to finish eating at least 2–3 hours before going to sleep. This allows your body to digest your meal before you lie down, reducing the risk of acid reflux and disturbed and restless sleep.

• Limit Caffeine: Caffeine can stay in our system for many hours, which is why it is good to avoid drinking after midday and avoid excess consumption. Caffeine also stimulates cortisol release which can also affect our sleep.

• Limit Alcohol: Though alcohol may help to make us feel relaxed and fall asleep, it can affect the quality of sleep we get, particularly REM sleep which is vital for memory consolidation, learning, and emotional processing. It may also irritate the gut. Try to avoid drinking alcohol in excess and too close to bedtime.

• Create a Relaxing Bedtime Routine: Wind down with calming activities such as reading, gentle yoga, or meditation. Avoid screens for at least an hour before bed, as blue light can suppress melatonin production.

• Keep Your Bedroom Cool and Dark: A cool, quiet, and dark environment is best for restorative sleep. Use blackout curtains, white noise machines or earplugs if necessary.

• Keep your Bed for Sleeping: Avoid activities such as watching screens, eating, using your phone or reading in bed, especially if you already have issues getting good sleep. Using your bed for sleep and intimacy only helps improve the association of your bed with sleep.

• Stay Physically Active: Regular exercise promotes better sleep and stimulates healthy digestion. Be mindful of very intense workouts right before bed however as some people may find it harder to wind down and fall asleep.

• Get outdoors during the day: Light exposure, especially in the morning, affects a person's circadian rhythms, which control daily patterns of sleep and wakefulness. Sunlight is significantly more intense than even the brightest indoor lighting, which is why it is vital to get exposure to outside light. Sunlight inhibits melatonin, helping you to stay awake during the day, leading to melatonin production at the appropriate time in the evening.

Final Thoughts

A good night’s sleep is more than just rest, it is a fundamental part of digestive health. If you’re struggling with bloating, irregular bowel movements or acid reflux, it may be worth taking a closer look at your sleep habits. By prioritising rest and maintaining a consistent routine, you can support both your gut and your overall health.

Sweet dreams and happy digestion!