diff --git a/HEARTBEAT.md b/HEARTBEAT.md
index 1268342..2de28f3 100644
--- a/HEARTBEAT.md
+++ b/HEARTBEAT.md
@@ -22,6 +22,15 @@ Check the following and notify only once per event (track in `memory/heartbeat-s
    
    **Work-end reminders**: When they indicate they're wrapping up or transitioning to wind-down, check `memory/brain-dump.json` for `recurring` items with `when: "evening"` and remind them (e.g., nose shower) before they get too deep into relaxation mode.
 
+   **📝 AUTO-LOG WIND-DOWN EVENTS** — Log to `memory/wind-down-log.json` immediately when these happen:
+   - User stops working / calls it a day
+   - Nose shower done
+   - In bed / winding down
+   - Trying to sleep
+   - Any sleep-related updates (couldn't sleep, woke up, etc.)
+   
+   Don't wait to be asked — this data is critical for analyzing sleep habits and optimizing the wind-down process.
+
 4. **Proactive calendar reminders**: Check CalDAV for upcoming events (see TOOLS.md for credentials). Only remind for events that require leaving home:
    - In-person / location-based: 1-2 hours before (account for travel)
    - Appointments (doctor, haircut, etc.): 1 hour before