Optimize: Sleep

The guideline first-line for chronic insomnia, ahead of pills; largest and most durable effect (~19 min faster to sleep, held at 12 months).

Reduce-lever: 400 mg within ~4-6 h of bed costs 45-51 min of sleep; cutting caffeine earlier is one of the highest-value free moves (it does not touch REM).

A cool (about 20-25 C), dark, quiet room; each 10 dB of night road noise roughly 2.5x's badly disturbed sleep.

Morning daylight anchors a delayed clock earlier (ES 0.34) and lifts sleep quality; free.

Passive body heating: a warm bath 1-2 h before bed shortens time to fall asleep, pooled across 13 studies.

Reduce-lever: a nightcap speeds onset but cuts REM and fragments the second half of the night; less before bed sleeps better.

A circadian tool: strong for jet lag and a delayed clock, modest (~7 min) for ordinary insomnia; 0.3-0.5 mg works as well as 3 mg.

Meaningful sleep-quality gain in women with sleep problems (PSQI SMD -0.54).

Reduce-lever, and a narrow one: interactive device use in bed costs sleep; blue-blocking glasses and Night Shift mode are no-effect, so do not sell them as the fix.

For restless legs with low ferritin only: cut RLS severity ~3.8 points; not a general sleep aid.

Beats a matched comparison (ES 0.33-0.54) but no better than established sleep therapies.

Older adults fell asleep ~17 min faster, on weak evidence.

Small sleep gain across 5 trials (SMD -0.59); trials small and several industry-linked.

Acupoint therapies improved sleep across 95 insomnia trials; low-cost and self-administered.

Moderately better self-rated sleep; gentle and free, tradition-supported.

Sleep improved in 5 of 8 trials, likely via calmer pre-sleep thoughts.