Sleep
Sleep runs on two systems: a circadian clock that decides when your body expects night, and sleep pressure — adenosine building the longer you are awake. Falling asleep on time requires both to line up, and arousal from stress, late caffeine, or bright light can override either one.
Supplements act on narrow parts of that machinery. Melatonin delivers the clock’s night signal on your schedule; magnesium and glycine nudge the winding-down side — GABA activity and core body temperature. None of them sedate you, and none outrank the basics: a consistent schedule, a dark room, and caffeine kept to the morning. The list below is ranked by evidence grade, caveats attached.
Ranked by evidence
- Melatonin 0.5–1 mg, 30–60 minutes before bed; raise only if a week at the low dose does nothing
- Magnesium glycinate 200–400 mg elemental in the evening; most useful when dietary intake runs low
- Ashwagandha 300–600 mg root extract in the evening; sleep effect rides on the stress effect
- Glycine 3 g powder 30–60 minutes before bed; evidence is small-trial only
- L-theanine 200 mg in the evening; calm-without-sedation profile, weak direct sleep data
Grades are per goal–ingredient pairing, hand-assigned from the evidence records linked on each monograph. Ingredients without a link have a monograph on the way.
What does not work (yet)
- Melatonin at retail-high doses (5–10 mg). Dose-ranging data show low doses matching high ones for sleep efficiency, with less next-day carryover. More is just more grogginess.
- Magnesium oxide. Poorly absorbed — mostly a laxative form. The sleep trials used better-absorbed forms in people whose intake ran low.
The list above is the general case. Your medications, current stack, budget, and other goals change it — sometimes a lot.