Hot Bath 40 °C — 90 min Pre-Sleep
A 15-minute 40 °C bath 90 minutes before lights-out raises then drops core temperature, accelerating sleep onset.
Take a 15-minute bath at 40 °C about 90 minutes before lights-out to raise and then drop core body temperature and accelerate sleep onset. It is the cleanest passive sleep intervention when a sauna is not available.
The protocol
- Timing: 90 min before sleep.
- Duration: 15 min.
- Frequency: as needed.
- Water temp: 40 °C.
- Prerequisites: hydrate, exit if dizzy.
What you get
- Faster sleep onset.
- Deeper early-night sleep.
- Muscle relaxation.
Contraindications
- Pregnancy (consult).
- Cardiovascular disease.
- Low blood pressure.
- Alcohol within 4 hours.
Evidence level
Medium. There is reasonable supporting evidence that pre-sleep warming followed by core-temperature drop shortens sleep onset; timing relative to bedtime matters.
Related protocols
Sources
AgeGen never invents studies and never recommends prescription drugs by brand. Biohacks are experiments, not prescriptions — honour the contraindications and talk to a clinician if a condition above applies to you.