The Nutrients That Help You Sleep Deeper

Why you're not sleeping deeply

Sleep isn't a single state. It's a cycle of stages. Light sleep, deeper sleep, REM sleep. Your body needs to cycle through all of them multiple times a night. If you're getting stuck in light sleep, it's usually because your nervous system can't fully relax and your body temperature can't drop enough to trigger deep sleep.

The culprits are usually the same: magnesium deficiency (blocks muscle relaxation), poor gut health (impairs serotonin production), excessive cortisol (keeps nervous system activated), or inadequate amino acids for neurotransmitter synthesis.

The fix isn't sleeping pills. It's feeding your body what it needs to sleep deeply on its own.

Magnesium: the muscle relaxant

Magnesium is responsible for over 300 enzymatic reactions in the body. It's particularly critical for muscle relaxation.¹ Without adequate magnesium, your muscles stay tense. Your nervous system stays activated. You're physiologically incapable of deep sleep.

Magnesium deficiency is rampant. Soil depletion means vegetables have less magnesium than they did decades ago. Stress depletes magnesium. Processed food is magnesium-poor. Most people in the modern world are running low.

The symptoms are obvious: muscle tension, irritability, anxiety, poor sleep quality, inability to relax, migraine headaches. All of these improve dramatically when magnesium is restored.

Food sources: dark leafy greens, nuts, seeds, whole grains, legumes, fish, and organ meats. Pumpkin seeds are extraordinarily rich. A handful provides roughly 200 mg. Almonds, cashews, dark chocolate, spinach. Realistically, many people need to supplement magnesium, especially if they're chronically stressed or have poor gut health.

Magnesium supplementation is safe. Start with 200-300 mg in the evening.¹ You'll notice sleep depth improving within 3-5 days. If you're very deficient, it might take a week or two, but the shift is profound once it happens.

You cannot sleep deeply if your muscles are tense. Magnesium is the nutrient that allows tension to release.

Glycine: the body temperature drop

Glycine is a simple amino acid. Your body makes some, but typically not enough.⁵ It serves a critical function in sleep: it helps your body temperature drop by promoting vasodilation (opening of blood vessels, especially in hands and feet).

Deep sleep requires a drop in core body temperature. Your body signals sleep onset partly through temperature reduction. If your core temperature stays elevated, deep sleep is suppressed. You stay in light sleep.

Glycine also has direct effects on the nervous system. It binds to glycine receptors in the spinal cord and central nervous system, promoting relaxation.² It's one of the few amino acids that actually reduces nervous system excitation.

Glycine is found primarily in animal foods, especially collagen-rich foods. Bone broth is extraordinarily rich in glycine. A single serving of good bone broth contains 1-2 grams. Skin, connective tissue, gelatinous cuts of meat. These are glycine sources.

If you're not eating bone broth or collagen-rich foods regularly, you're probably deficient in glycine. The result is poor sleep quality and inability to regulate body temperature properly.

Supplemental glycine (3-5 grams before bed) is safe and effective. Or, drink bone broth daily and you're covered. Both work. Bone broth also provides minerals and other amino acids that support sleep.

B6 and neurotransmitter balance

B6 (pyridoxine) is a cofactor for the enzymes that synthesise neurotransmitters. Serotonin, GABA, melatonin. All of these require B6.⁴

Low B6 shows up as poor sleep quality, mood instability, and waking too early. You're not making enough neurotransmitters to sleep deeply and stay asleep.

B6 is found in animal foods, nuts, seeds, and whole grains. Liver is extraordinarily rich. Fish, chickpeas, potatoes. If you're eating varied whole foods, B6 deficiency is rare. But if you're eating processed food, B6 is usually low.

B6 supplementation at 50-100 mg can improve sleep quality. Combined with magnesium and glycine, it's a powerful combination. But food is better. Eat liver once a week and you're well-covered.

The serotonin-sleep connection

Serotonin is the precursor to melatonin. About 95% of your body's serotonin is made in the gut. If your gut health is poor, serotonin production is suppressed. If serotonin is low, melatonin is low. If melatonin is low, you can't initiate sleep properly.

The gut bacteria that produce serotonin depend on a healthy gut lining and a diverse microbial community. Dysbiosis (imbalanced microbiota) suppresses serotonin-producing bacteria. Gut inflammation impairs serotonin absorption and metabolism.

The fix: heal the gut. Bone broth, fermented foods, prebiotic foods (garlic, onions, chicory), colourful vegetables, and adequate fibre. Most people's sleep improves noticeably within 4-6 weeks of addressing gut health.

The amino acid tryptophan is the precursor to serotonin. It's found in animal foods, nuts, seeds, and whole grains. But simply eating tryptophan doesn't guarantee serotonin production. Your gut health and B6 status are equally important.

The cortisol-sleep feedback loop

Cortisol is your stress hormone. It's supposed to be high in the morning and drop through the day, hitting its lowest point around midnight. If cortisol stays elevated at night, sleep is impossible. You'll either struggle to fall asleep or wake in the early morning hours (2-3 AM is classic elevated night-time cortisol).

The nutrients that support cortisol regulation are the same ones we've discussed. Magnesium, B vitamins, sufficient carbohydrate (signals safety to the nervous system), adequate salt and minerals. Also critical: consistent sleep schedule, no bright light after sunset, and stress management.

If your cortisol is chronically elevated (from stress, under-eating, excessive exercise, or chronically poor sleep), fixing sleep requires addressing these inputs. Feed your body correctly, reduce stress, and sleep improves.

Putting it together

Deep sleep is a physiological state. You can't think your way into it. You can't force it. But you can create the nutritional and environmental conditions that allow it.

Start with magnesium. Add glycine (via bone broth or supplementation). Eat liver or other B-rich foods. Heal your gut. Manage cortisol through stress reduction and proper nutrition. Sleep depth will improve measurably within weeks.

Don't expect overnight change. Your body has to rebuild its nutrient stores. But consistency works. By week four, most people notice they're sleeping more deeply, waking less often, and feeling more rested in the morning. By week eight, the shift is profound.

The nutrients are the foundation. Environment is the walls. Together, they create a space where deep sleep naturally happens.

The supplement question

Can you fix sleep with supplements alone? Rarely. Supplements are tools, not replacements for food. If you're eating processed food, your supplements will have limited effect. But if you're eating well and still struggling, supplementation can be the final piece.

Magnesium supplementation is generally safe and effective. Glycine supplementation is safe. B-complex vitamins are safe. Bone broth is food, so it's the best source of both glycine and minerals. If you're starting from a place of real deficiency, supplementation can speed the process. But food is always the foundation.

The environment matters

Nutrition is the interior piece. But sleep also depends on environment: darkness, coolness, quiet. If you're in a bright bedroom, exposed to blue light from screens, your melatonin production is suppressed no matter what you eat. If your room is warm, your body temperature won't drop properly. If there's noise, your nervous system stays activated.

Feed the body the nutrients it needs and create the environment where sleep can happen. The combination is powerful.

Nutrient timing and absorption for sleep

Taking magnesium at 9 PM is less effective than taking it at dinner or even with breakfast, because your digestive system processes nutrients more efficiently during active hours. Magnesium competes with calcium and zinc for absorption, so timing and meal composition matter significantly.

The best approach is distributing sleep-supporting nutrients throughout the day rather than cramming them into a pre-bed supplement. Eat collagen-rich foods (bone broth, fish skin) at breakfast or lunch so your body has glycine available when you need it. Include protein and fat at dinner to slow gastric emptying and maintain steady amino acid availability through the night.

Magnesium is absorbed better when taken with food that contains some carbohydrate, as the insulin response helps drive mineral uptake into cells. So a magnesium supplement with dinner (which includes carbs from vegetables or roots) works better than magnesium in isolation before bed. Similarly, B vitamins are water-soluble and absorbed better when eaten with a meal.

The irony is that trying to perfect supplement timing often creates more stress than it solves. If you're eating whole foods consistently, you're getting these nutrients. The simpler approach: eat nutrient-dense whole foods across your meals, and your nutrient status will reflect that consistency. Sleep quality improves naturally.

You don't need the perfect supplement protocol. You need consistent whole food nutrition and a calm nervous system.

The bottom line

You don't have to accept poor sleep as your baseline. Your body isn't broken. It's undernourished. Feed it magnesium, glycine, B6, and the building blocks for serotonin. Heal your gut. Manage your stress. Create an environment where sleep can happen. And it will. Deep, restorative sleep is your birthright. You've just been deprived of the nutrients that make it possible.

References

1. 1. National Institutes of Health, Office of Dietary Supplements. Magnesium: Fact Sheet for Health Professionals. https://ods.od.nih.gov/factsheets/Magnesium-HealthProfessional/ [accessed May 2026].
2. 2. Bannai M, Kawai N. New therapeutic strategy for amino acid medicine: glycine improves the quality of sleep. Journal of Pharmacological Sciences. 2012;118(2):145-148. https://pubmed.ncbi.nlm.nih.gov/22293292/
3. 3. Kawai N, Sakai N, Okuro M, et al. The sleep-promoting and hypothermic effects of glycine are mediated by NMDA receptors in the suprachiasmatic nucleus. Neuropsychopharmacology. 2015;40(6):1405-1416. https://pmc.ncbi.nlm.nih.gov/articles/PMC4397399/
4. 4. National Institutes of Health, Office of Dietary Supplements. Vitamin B6: Fact Sheet for Health Professionals. https://ods.od.nih.gov/factsheets/VitaminB6-HealthProfessional/ [accessed May 2026].
5. 5. Melendez-Hevia E, De Paz-Lugo P, Cornish-Bowden A, Cardenas ML. A weak link in metabolism: the metabolic capacity for glycine biosynthesis does not satisfy the need for collagen synthesis. Journal of Biosciences. 2009;34(6):853-872. https://pubmed.ncbi.nlm.nih.gov/20093739/