The small home upgrade that quietly fixed my sleep before any sleep advice did

I tried most of the standard sleep advice — consistent bedtime, no screens, cooler room — with modest results, before a much smaller and cheaper change made a bigger difference than any of it: blackout curtains, replacing the light-filtering ones I'd had for years without really examining them.

Streetlight and early dawn light had been leaking in at a low enough level that I never consciously noticed it, but apparently enough to disrupt the last hour or two of deeper sleep every single night. The curtains cost less than a single session with most of the sleep-optimization advice I'd tried, and did more for how rested I felt than any of it.

I'd recommend checking this before any more elaborate sleep intervention. It's the most boring possible fix, and in my case it was also the correct one, hiding in plain sight behind curtains I'd stopped actually looking at.

Related reading: The Homeowner's Guide to Fixes That Actually Hold (Not Just Look Fixed) and Why your drywall patch keeps showing through paint, and it's not the paint.