Your gut is linked to your brain in surprising ways, and you may be losing sleep over it. Research into the gut-brain axis reveals that, amazingly, microbes in your gut can affect your mood – and along with that, your sleep patterns. Sleep disorders and depression are common among people with gut problems like irritable bowel syndrome (IBS), Crohn’s disease or ulcerative colitis. This association goes both ways: your gut can affect – or be affected by – your mood and sleep patterns.
The idea that your brain can affect your gut seems to imply that you could treat gut problems with psychiatry, which is nutty. Except that it seems to work. Research suggests that cognitive behavioral therapy, which is aimed at the mind, can ease symptoms of IBS – including sleeplessness. What an unexpected way to treat gut problems! Problems with sleep, mood and gut turn out to be inextricably bound together.
Microbes can secrete dozens of human neuroactive chemicals, which gives them a disturbing amount of power over our brain. They can send messages slowly through the endocrine system, somewhat faster through the immune system, and at lightning speed through the vagus nerve. A well-balanced microbiota is a wonderfully silent partner, but a poorly balanced one will end up with a few dominant “bully” species that can make a lot of fuss.
These top dogs, without counterbalancing microbes, tend to act as disease-causing pathogens. When they don’t get what they want, they can release neurotoxins like ammonia that affect sleep, stress, and brain function in general.
The cycles of life
All living things have chemical reactions that cycle over and over again. Some, like the Krebs cycle you vaguely remember from high school, are fast, converting glucose to energy at a madcap pace. Others, like the circadian cycle, take 24 hours. The name circadian means “about a day,” and even bacteria display these leisurely daily oscillations.
It affects us from early on. Without circadian rhythms, we might just be blobs. Dr. Ann Kiessling of the Bedford Research Institute, which investigates stem cell therapies, says:
“Stem cells may especially need circadian signals to differentiate into specific cell types, such as neurons or bone marrow. The first evidence of circadian oscillator proteins is at the late 2-cell stage in mice, when at least 10% of stem cells are expressing circadian oscillator proteins, but not synchronized. Then as the cells differentiate, they start to synchronize. We don’t know what triggers that, but differentiation and synchronization seem to be coupled.”
Each cell in your body runs a tiny version of the circadian clock and needs to cooperate with all its neighbors, so it’s important for them to continuously synch up. In animals, the brain controls this daily cycle with a sleepy-time chemical called melatonin, which builds up when it gets dark at night to make you sleepy and drops in the morning to wake you up.
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This internal clock wants to synchronize with daylight, explaining why traveling across time zones, artificial lights, and cloudy climates all mess with your rhythms. When your body’s rhythm is disrupted, your microbiota also gets disrupted, which can boost the numbers of poor team players like Candida at the expense of beneficial bacteria like Lactobacillus and Bifidobacteria. That helps to explain why shift workers have higher rates of gut issues, sleep problems and depression.
You can mess up your daily rhythm by simply keeping your lights on in the evening. It’s not a small effect: Evening light can delay the release of melatonin by up to two hours.