10 minutes of morning sunlight and my afternoon energy crashes

Background

I hit a wall around 2–3pm almost every day. I'd read that morning light helps set your circadian rhythm, so I wanted to see whether a small, free habit would do anything measurable for me.

Method

• Weeks 1–2 (baseline): normal routine, no deliberate light exposure. Rated my afternoon energy at 3pm on a 1–5 scale.
• Weeks 3–6 (intervention): went outside for ~10 minutes within 30 minutes of waking, no sunglasses. Same 3pm rating.

I also noted each day whether I had a "noticeable crash" (yes/no) and the weather (sunny / overcast).

Results

Mean afternoon energy rose from 2.4 → 2.9. Crash days fell from 11/14 in baseline to 17/28 in the intervention period (~79% → ~61%).

Splitting by weather during the intervention: on sunny days my average rating was 3.2, on overcast days 2.5 — close to baseline.

Discussion

There seems to be a real but modest effect, and it appears light-dose dependent — overcast mornings barely moved the needle. Confounds: I started this in spring as days got longer, and simply going outside may have woken me up in other ways (movement, cold air).

Conclusion

Cheap, pleasant, and probably slightly helpful for me — especially on sunny days. Not a cure for my afternoon slump. I'm keeping the habit and may next test whether a 10,000-lux light box helps on overcast mornings.