Single questions, honestly answered.
Each brief takes one question about sleep, light, timing, or the things people say about them, and works through it: what the evidence looks like, who it was measured in, and what is still open. Where the answer is "we do not know yet", the brief says that.
All research briefs
No briefs published yet
The first briefs are in review. A brief does not publish until its sources are in place, so this page stays empty rather than filling with claims we cannot yet point at.
What the ratings mean.
Strong
A well-described mechanism supported by repeated findings across independent groups, with results that point the same direction.
Moderate
Consistent enough to be useful, but the size of the effect, the conditions it needs, or the people it was measured in leave real room to move.
Emerging
Early or narrow work. The idea is plausible and being actively studied, but it has not yet been tested widely enough to know how far it travels.
Contested
Credible work disagrees. Different methods, populations, or definitions produce different answers, and the disagreement has not resolved.