Inositol for Sleep: What Studies Show, How Much and When to Take It

Inositol for sleep has been tested in one randomized trial so far: 60 pregnant women who took 2 g of myo-inositol once a day at night for 10 weeks ended with better sleep quality scores than those on placebo. That makes the evening the natural time to take it. Many people use inositol at night as one part of a wind-down drink, alongside glycine, magnesium and L-theanine, which have sleep studies of their own.

Key Takeaways

• Myo-inositol is the main form of inositol in supplements and the one used in sleep research.
• In a 10-week trial, 2,000 mg of myo-inositol taken at night improved overall sleep quality, sleep duration and sleep efficiency scores in pregnant women compared with placebo (Mashayekh-Amiri et al., 2022).
• That trial dissolved the powder in water and took it once daily at night, which is the simplest answer to the morning or night question for sleep.
• A safety review found that only the highest amount studied, 12 g a day, caused mild stomach effects (Carlomagno and Unfer, 2011).
• Inositol pairs well with glycine, magnesium and L-theanine, each studied for sleep in its own trials.

What Is Inositol?

Inositol is a sugar-like compound your body makes and also gets from food. Myo-inositol is its most common form and the one sold as a powder or capsule. Researchers describe myo-inositol as a marker of glial cells, the support cells of the brain, in some brain regions, and suggest it may play a part in sleep processes (Mashayekh-Amiri et al., 2022). Our guide to myo-inositol covers its other uses, food sources and the difference between myo-inositol and D-chiro-inositol. This guide focuses on sleep: what was studied, how much, and when to take it.

What the Research on Inositol and Sleep Shows

The clearest sleep study is a randomized, double-blind, placebo-controlled trial in Iran. It enrolled 60 women with low-risk single pregnancies from 14 weeks of pregnancy. For 10 weeks, from week 14 to week 24, one group took a powder with 2,000 mg of myo-inositol and 200 mcg of folic acid, and the other took a placebo with 400 mcg of folic acid (Mashayekh-Amiri et al., 2022). The trial registration describes one sachet dissolved in a glass of water once daily, taken at night (IRCT trial record).

Sleep was measured with the Pittsburgh Sleep Quality Index, a standard sleep questionnaire. After the 10 weeks, the myo-inositol group had better scores than the placebo group for:

Measure	Result with myo-inositol vs placebo
Overall sleep quality score	Better
How people rated their own sleep	Better
Sleep duration	Better
Sleep efficiency (time asleep compared with time in bed)	Better

It was one small trial in one group, pregnant women, so it is an early result rather than the final word. Anyone pregnant or breastfeeding should talk with their healthcare provider before starting any supplement. Still, it is a useful guide to how much and when: 2 g once a day, at night, for weeks rather than a single night.

Inositol for Sleep Dosage

The sleep trial used 2,000 mg (2 g) of myo-inositol a day. That is a useful anchor for anyone taking inositol with sleep in mind. Higher amounts have been studied for other reasons, and a safety review found that only the highest amount studied, 12 g a day, caused mild stomach effects such as nausea, gas and diarrhea, and that the severity did not rise with the dose (Carlomagno and Unfer, 2011).

• Amount studied for sleep: 2 g of myo-inositol once a day.
• Form: powder dissolved in water, which makes gram amounts easy to take in one drink.
• Check the label: look at the milligrams per serving to see how close it comes to 2 g.

Best Time to Take Inositol for Sleep: Morning or Night?

For sleep, take it in the evening. The pregnancy trial gave it once daily at night (IRCT trial record), so evening is the timing with research behind it. A practical routine:

• Before bed: mix your inositol into a glass of water 30 to 60 minutes before bed, so it becomes part of your wind-down.
• Same time each night: the trial measured change over 10 weeks of daily use, so consistency matters more than the exact minute.
• Splitting a larger amount: if you take inositol for other reasons as well, some people split it between morning and evening. For sleep, keep at least part of it in the evening.

Inositol With Glycine, Magnesium and L-Theanine

Inositol is rarely taken alone for sleep. It is usually one part of an evening blend, next to ingredients with their own sleep studies. Here is what each was studied at:

Ingredient	Amount studied	What the study measured
Myo-inositol	2 g at night, 10 weeks	Better sleep quality scores in pregnant women
Glycine	3 g before bed	Shorter time to fall asleep and to reach deep sleep, less daytime sleepiness, in people not sleeping well (Yamadera et al., 2007)
Magnesium	250 mg as bisglycinate, 30 to 60 minutes before bed, 4 weeks	A small improvement in a sleep questionnaire score in 155 adults reporting poor sleep (Schuster et al., 2025)
L-theanine	200 mg a day, 4 weeks	Better overall sleep scores and better scores for time to fall asleep in 30 healthy adults (Hidese et al., 2019)

These ingredients work in different ways and are commonly combined. Each was studied on its own, so think of an evening blend as a routine built from parts that each have their own research. For more on each partner, see glycine for sleep, magnesium glycinate for sleep, L-theanine for sleep and tart cherry for sleep, or our glycine ingredient page.

Who Might Choose Inositol for Sleep

• You want a sleep routine without melatonin. Inositol is one of several options covered in our guide to sleep supplements without melatonin.
• You like a nightly drink. Inositol dissolves easily in water, so it suits a bedtime glass rather than a handful of capsules.
• You want a gentle, steady approach. The trial measured changes over 10 weeks of daily use, not on the first night.
• You want something calming without a drink. L-theanine is another evening option, and it comes in forms other than powders.

Inositol Side Effects and Who Should Check First

Most people tolerate inositol well. In the safety review, mild stomach effects such as nausea, gas and diarrhea appeared only at the highest amount studied, 12 g a day, which is several times the 2 g used for sleep (Carlomagno and Unfer, 2011). If your stomach is sensitive, start with a smaller amount and take it in a full glass of water. Talk with your clinician first if you are pregnant or breastfeeding, or if you take prescription medicine.

Where Our Sleep Powder Fits

Our Melatonin-Free Sleep Powder is coming soon. It brings myo-inositol together with tart cherry, 3 g of glycine, 200 mg of magnesium from two gentle forms and apigenin, mixed in water 30 to 60 minutes before bed, with no added melatonin, no 5-HTP and no added sugar or sweeteners. Join the waitlist on the product page to hear when it launches. Like most nightly routines, benefits build with consistent daily use: months 1 to 2 can bring early changes, and 3 months and beyond is where the full benefit builds.

If you would rather not mix a drink, our Theanine Nasal Spray gives 36 mg of L-theanine per 2-spray serving, with alkaline water as the only other ingredient. It is caffeine free, absorbed through the lining of the nose, so some of each dose skips digestion, and it is part of our Sleep Stack and Focus Stack. For more on rest, visit our sleep health hub.

Frequently Asked Questions

Does myo-inositol help you sleep?

In a 10-week trial, pregnant women taking 2 g of myo-inositol at night had better sleep quality, sleep duration and sleep efficiency scores than those on placebo. It is an early result in one group.

What is the best time to take inositol for sleep?

In the evening. The sleep trial gave it once daily at night, and many people take it 30 to 60 minutes before bed.

Should I take inositol in the morning or at night?

For sleep, take it at night. If you also take inositol for other reasons, you can split the amount, but keep part of it in the evening.

Can I take inositol right before bed?

Yes. Dissolve it in a glass of water as part of your bedtime routine, ideally 30 to 60 minutes before lights out.

How much inositol should I take for sleep?

The sleep trial used 2 g of myo-inositol once a day. Ask your clinician about your own amount if you take medication.

How long does inositol take to work for sleep?

The trial measured changes after 10 weeks of daily use, so give it time rather than judging it on the first few nights.

Can I take inositol with magnesium and glycine?

Yes, they are often combined in evening blends. Glycine and magnesium each have their own sleep studies, at 3 g and 250 mg respectively.

Is inositol the same as myo-inositol?

Myo-inositol is the most common form of inositol and the one used in the sleep trial, so most labels that say inositol mean myo-inositol.

Does inositol have side effects?

Most people tolerate it well. Mild stomach effects were seen only at 12 g a day, the highest amount studied.

Sources

• Mashayekh-Amiri S, et al. The impact of myo-inositol supplementation on sleep quality in pregnant women: a randomized, double-blind, placebo-controlled study. Journal of Maternal-Fetal and Neonatal Medicine, 2022. https://pubmed.ncbi.nlm.nih.gov/32933356/
• Iranian Registry of Clinical Trials. The impact of myo-inositol supplementation with sleep hygiene education on sleep quality in pregnant women, IRCT20160208026446N3. https://en.irct.ir/trial/31296/pdf
• Carlomagno G, Unfer V. Inositol safety: clinical evidences. European Review for Medical and Pharmacological Sciences, 2011. https://europeanreview.org/?p=1015
• Yamadera W, Inagawa K, Chiba S, et al. Glycine ingestion improves subjective sleep quality in human volunteers, correlating with polysomnographic changes. Sleep and Biological Rhythms, 2007. https://doi.org/10.1111/j.1479-8425.2007.00262.x
• Schuster J, Cycelskij I, Lopresti A, Hahn A. Magnesium bisglycinate supplementation in healthy adults reporting poor sleep: a randomized, placebo-controlled trial. Nature and Science of Sleep, 2025. https://doi.org/10.2147/NSS.S524348
• Hidese S, Ogawa S, Ota M, et al. Effects of L-theanine administration on stress-related symptoms and cognitive functions in healthy adults: a randomized controlled trial. Nutrients, 2019. https://pubmed.ncbi.nlm.nih.gov/31623400/

These statements have not been evaluated by the Food and Drug Administration. This content is for education and is not medical advice. Our products are not intended to diagnose, treat, cure or prevent any disease. Talk with a healthcare provider before starting a new supplement if you are pregnant, breastfeeding or taking medication.