Sleep, Gut Health & GLP-1: How Poor Sleep Affects Your Appetite and Metabolism

By Dr. Madusha Peiris

Most people think of sleep as something that restores the brain and helps us feel alert, focused and emotionally balanced. But one of the biggest lessons from researching gut–brain communication is that poor sleep affects far more than your energy levels: it has a direct impact on your gut, your hormones and your ability to regulate hunger and metabolism.

Your gut and your brain communicate constantly through the gut–brain axis, using nerves, hormones and even signals from your gut microbes. When sleep is cut short, this communication network becomes dysregulated, affecting digestion, cravings and metabolic function.

Why Sleep Matters for Your Gut

Virtually every cell in your body contains a glucocorticoid receptor — a receptor that responds to cortisol, your main stress hormone. These receptors also regulate circadian rhythm, meaning sleep influences nearly every cell in the body (Nicolaides N. C. et al., 2020).

Cortisol naturally peaks in the early morning to align your internal clock with the day–night cycle. Irregular sleep, chronic stress, caffeine, alcohol or late nights disrupt this process. Over time this misalignment can affect metabolism, memory, mood and — importantly — gut function (Yang, D. et al., 2023).

Your gut operates on its own circadian rhythm too. The intestinal lining, the microbes living within it and the hormones they release all follow 24-hour cycles. High-quality sleep helps regulate:

• digestion
• nutrient absorption
• gut barrier strength
• inflammation
• gut-hormone release

When sleep is poor, these systems become disrupted and gut symptoms often follow (Yang, D. et al., 2023).

The Gut & Melatonin

The gut is the body’s largest source of melatonin, stored and released by enterochromaffin cells. In our 2022 paper (Peiris et al., Gut 2022), we demonstrated how Elcella activates enterochromaffin cells, increasing melatonin release. Melatonin plays a key role in promoting calmness and preparing the body for rest — highlighting another way the gut influences sleep quality.

Learn how Elcella works on our results page

Hormonal Chaos: GLP-1, Ghrelin, PYY and Other Satiety Hormones

This is where most people begin to notice symptoms. When you are sleep-deprived, hunger and fullness hormones shift out of balance.

Under normal conditions, appetite is regulated by multiple gut and brain-derived hormones, including:

• Ghrelin – the hunger hormone produced in the stomach
• GLP-1 – promotes fullness, supports insulin release and slows digestion
• PYY – a satiety hormone released after eating
• OXM, CCK and amylin – additional fullness hormones involved in regulating appetite

So hunger and fullness are not controlled by only GLP-1, ghrelin and PYY. It's a whole network. But the research is clear: lack of sleep disrupts this hormonal balance dramatically.

What Happens When You Do Not Sleep Well?

Research shows that even one night of restricted sleep can impair appetite control (Spiegel et al., 2004; Taheri et al., 2004; Buxton et al., 2010; Benedict et al., 2011; Yang, D. et al., 2023).

Here’s what studies consistently find:

• Ghrelin increases, making you feel hungrier.
• GLP-1 decreases, reducing fullness and weakening insulin response.
• PYY decreases, making it harder to feel satisfied after eating.
• Other satiety hormones (including CCK and OXM) show reduced signalling.
• Cortisol rises later in the day, interfering with insulin and gut-hormone communication.
• The hypothalamus becomes more responsive to hunger signals and less responsive to satiety cues.
• Cravings intensify, especially for high-fat, high-carbohydrate foods.
• Metabolism slows, and blood sugar becomes harder to control.

Learn about PYY in our blog written by Dr Madusha Peiris.

This helps explain why sleep deprivation can’t simply be “worked off” through exercise — the hormonal disruption runs much deeper.

Sleep, Gut Microbes and Digestion

Your gut microbiota (the trillions of bacteria living in your intestines) also operate on a circadian rhythm. Their composition and activity shift across the day, supporting digestion, inflammation control and hormone production (Yang, D. et al., 2023).

Scientific studies show that poor or irregular sleep can:

• reduce microbial diversity (Zhu et al., 2018)
• increase pro-inflammatory species (Poroyko et al., 2016)
• weaken the gut barrier (McHill et al., 2019)
• impair GLP-1 release (Reynolds et al., 2017)
• disrupt glucose metabolism and increase insulin resistance (Benedict et al., 2011)

Even one night of disrupted sleep may alter the microbiome (Yang, D. et al., 2023).

Read our blog on why gut health is important for weight loss, written by Dr Rubina Aktar.

Many people notice this as bloating, sluggish digestion, irritability or stronger cravings the next day.

Practical Tips: Sleeping for Better Gut and Hormone Health

Here are some of the strategies I use personally and recommend:

1. Keep a consistent schedule
   Wake and sleep at the same time daily. This strengthens your circadian rhythm.
2. Get morning light
   Natural morning light helps reset your clock and regulates gut-hormone timing.
3. Avoid late-night eating
   Your gut needs time for rest and repair.
4. Create a sleep-friendly environment
   Cool, dark and quiet rooms support deeper sleep. Reduce screen time before bed.
5. Manage stress
   Elevated cortisol can disrupt gut barrier function and sleep. Breathwork, stretching or reading can help.

Read our article on our top tips for managing your gut health.

Final Thoughts

You cannot out-diet or out-exercise poor sleep. Your gut hormones, metabolism and microbiome all rely on high-quality, consistent rest.

The next time you’re tempted to stay up late, remember that both your gut and your future self will benefit from choosing sleep.

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Interesting articles:

Peiris M, Aktar R, Reed D, Cibert-Goton V, Zdanaviciene A, Halder W, Robinow A, Corke S, Dogra H, Knowles CH, Blackshaw A. Decoy bypass for appetite suppression in obese adults: role of synergistic nutrient sensing receptors GPR84 and FFAR4 on colonic endocrine cells. Gut. 2022 May;71(5):928-937. doi: 10.1136/gutjnl-2020-323219.

Nicolaides NC, Chrousos G, Kino T. Glucocorticoid Receptor. Endotext. 2020.

Deng-Fa Yang et al., Acute sleep deprivation exacerbates systemic inflammation and psychiatry disorders through gut microbiota dysbiosis and disruption of circadian rhythms, Microbiological Research, 2023.