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SYMPTOMS

Poor sleep

Everyday reasons for poor sleep, what to ask your doctor to check, and which nutrients have been studied.

Also described as: insomnia, trouble sleeping, sleep badly, waking up at night, wake up at 3, light sleeper, restless sleep, sleepless

Common everyday causes

Not enough restorative sleep

Under 7 hours, or broken sleep, lowers energy, focus, mood and immune defenses and raises cravings the next day. No test. Track sleep for a week; see a doctor if it lasts more than 3 months (CBT-I is first-line).

Stress load (your stress response on overdrive)

Ongoing stress keeps cortisol and adrenaline up: wired-but-tired, poor sleep, cravings, gut upset, shedding and lower libido. No routine test is reliable (a morning cortisol is only a snapshot).

Body clock out of sync

Late light, screens, irregular hours and shift work push your body clock later, so sleep won’t come when you need it. No test. Morning daylight and a steady wake time reset the clock.

Low magnesium

Magnesium relaxes muscles and nerves and is used in hundreds of energy reactions. Diet, stress, alcohol, acid reducers and water pills all lower it. Ask for a red-blood-cell (RBC) magnesium test; serum magnesium misses most low levels.

Caffeine timing and amount

Caffeine lasts 5–6 hours: afternoon coffee steals deep sleep, and too much drives jitters, a racing heart and the afternoon crash. No test — try no caffeine after noon for 2 weeks.

Hormone shifts of perimenopause and menopause

Falling and swinging estrogen drives hot flashes, night waking, mood changes and lower libido, usually from the early 40s. Diagnosis is by symptoms and cycle changes; hormone tests swing too much to rely on. Ask your doctor about hormone therapy or non-hormonal options.

What’s been studied

• L-theanine

  For sleep debt.

• Rhodiola

  For stress load.

• Melatonin

  For body clock.

• Vitamin E

  For menopause transition.

• Magnesium

  For sleep debt.

• Glycine

  For sleep debt.

From the Journal

• Magnesium glycinate vs citrate vs oxide: which form should you take?

  Glycinate, citrate, oxide, malate, threonate and taurate compared on magnesium content, absorption, gut comfort and capsule space, plus the 350 mg supplement limit and medicine timing.

• Which supplements help you sleep? What the research shows

  Magnesium, L-theanine, melatonin, saffron, glycine and tart cherry: what the trials found, the doses studied, and when poor sleep is a reason to see a doctor instead.

apiece asks a few quick questions about poor sleep in its quiz to tell these causes apart, and suggests only ingredients studied for the likely ones.

Questions

What can cause poor sleep?

Common everyday reasons include sleep debt, stress load, body clock, low magnesium, caffeine. A doctor can help find which applies to you.

What tests can help explain poor sleep?

Ask your doctor about: No test. Track sleep for a week; see a doctor if it lasts more than 3 months (CBT-I is first-line); No routine test is reliable (a morning cortisol is only a snapshot); No test. Morning daylight and a steady wake time reset the clock; a red-blood-cell (RBC) magnesium test; serum magnesium misses most low levels; No test — try no caffeine after noon for 2 weeks; Diagnosis is by symptoms and cycle changes; hormone tests swing too much to rely on. Ask your doctor about hormone therapy or non-hormonal options.

Which supplements are studied for poor sleep?

Depending on the cause: L-theanine, Rhodiola, Melatonin, Vitamin E, Magnesium, Glycine. Some only make sense with a lab result (for example iron only when ferritin is low).*

*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease. This page is general information, not medical advice. Check with your doctor or pharmacist before starting a supplement, especially if you take medication, are pregnant or nursing, or have a health condition. Updated 2026-10-21.