Hypothesis

Direct outdoor light exposure in the morning sets the circadian anchor, leading to earlier and better sleep onset.

What I changed

Walk outside (no sunglasses) for 10–15 minutes within 30 minutes of waking, every day.

What I measured

Subjective sleep quality (1–10), time to fall asleep, morning alertness (1–10).

Result

Average sleep quality increased from 6.2 to 7.8. Time to fall asleep reduced from ~25 to ~12 minutes.

Conclusion

Strong positive effect. Now a permanent part of morning routine.