Sleep is when the body does its actual repair work — clearing metabolic waste from the brain, consolidating memory, regulating hormones, repairing tissue, and recalibrating the immune system. Skimp on it for years and every other longevity effort delivers less.
What good sleep actually does
- Clears beta-amyloid and metabolic waste from the brain
- Regulates appetite hormones leptin and ghrelin
- Restores insulin sensitivity
- Supports growth hormone release for tissue repair
- Consolidates learning and emotional processing
The non-negotiables
- Consistent bed and wake times — even on weekends
- A cool, dark, quiet room
- Morning sunlight within 30 minutes of waking
- No caffeine after early afternoon
- A wind-down routine that's not your phone
When to dig deeper
If you're doing the basics and still waking tired, it's worth investigating sleep apnea, hormone shifts (especially perimenopause), low iron or ferritin, and elevated nighttime cortisol. Sleep is the foundation — fix it before optimizing anything else.