Sleep & Circadian Rhythm

Sleep is the most leveraged longevity habit most people can improve. Timing, light, sound, and temperature all matter.

Guides

Evidence: Supported

A Better Sleep Environment: Light, Sound, Temperature, and Air

Your bedroom is a set of physiological signals. Here's how to tune each one, ranked by evidence and cost.

Published Jul 12, 2026

Evidence: Emerging

Binaural Beats: What They Are, What Studies Suggest, and What Remains Uncertain

A genuinely interesting auditory phenomenon with promising-but-mixed evidence — here's an honest map of it.

Published Jul 12, 2026

Evidence: Established

Environmental Noise, Sleep, and Health: What the Evidence Actually Says

Noise is one of the best-documented environmental health exposures — and one of the most fixable.

Published Jul 12, 2026

Evidence: Established

The Sonic Vitality Guide to Healthy-Aging Foundations

Before supplements, devices, or protocols: the six foundations with the strongest evidence for aging well.

Published Jul 12, 2026

Related research

Evidence: Supported

Light exposure during sleep associated with cardiometabolic effects and impaired sleep physiology

Randomized trial · 2022 · Healthy young adults in a laboratory sleep setting

One night of sleeping in moderate room light (100 lux) versus dim light (<3 lux) increased nighttime heart rate, decreased heart-rate variability, and increased next-morning insulin resistance.

Evidence: Established

WHO guidelines identify environmental noise as a significant public-health risk

Guideline · 2018 · European populations exposed to transportation and leisure noise

Chronic exposure to environmental noise above recommended levels is associated with sleep disturbance, annoyance, and increased risk of ischaemic heart disease; WHO issues exposure-limit recommendations for road, rail, aircraft, wind-turbine, and leisure noise.

What remains uncertain Every topic on this site has open questions — that's how science works. Individual guides call out specific uncertainties, and our methodology explains how we grade what we publish.