**Most important metric: sleep latency (`sleep_latency_min`). Most important category: primary bedtime app (`primary_bedtime_app`).** I chose these for two reasons: - The dataset's purpose is to decide whether cutting bedtime phone use reduces sleep latency and sleep debt, and which app segments to target. - Across the six bedtime apps, sleep latency separates them more than any other outcome I compared. Average total sleep hours barely moves (6.17 to 6.38 h). **How sleep latency varies by app** (average minutes to fall asleep, from the per-app summary I queried): | App | Average latency | Users | |---|---|---| | TikTok / Reels | 46.1 | 2,198 | | Instagram / Reddit | 42.5 | 1,630 | | YouTube | 39.1 | 1,928 | | Messaging / Chat | 38.3 | 847 | | Streaming (Netflix/Hulu) | 36.4 | 1,301 | | News / Reading | 33.2 | 596 | - **Gap between apps:** TikTok / Reels users take about 13 minutes longer to fall asleep than News / Reading users, roughly 39% more. The medians show the same order (43.0 vs 31.8 min). - **Other outcomes line up with latency:** - Next-day fatigue is highest for TikTok / Reels at 4.16 and lowest for News / Reading at 3.33. - Average sleep is shortest for TikTok / Reels (6.17 h) and Instagram / Reddit (6.21 h), and longest for News / Reading (6.38 h) and Streaming (6.36 h). - Average snoozes follow the same pattern, from 3.01 for TikTok / Reels down to 2.39 for News / Reading. - **Other behaviours barely differ by app:** screen brightness (about 55%), caffeine after 5pm (32–35 mg) and physical activity (35–36 min). **Caveats** - This is observational data, so the gap does not prove the app causes slower sleep onset. - Age differs by app and could account for part of the gap. TikTok / Reels users are youngest (average 31.1) and News / Reading users oldest (38.0). - Short-form social video (TikTok / Reels, then Instagram / Reddit) is the clearest segment to target for sleep-hygiene interventions. Checking whether the gap holds within age bands would be a sensible next step. ```json {"charts": [{"kind": "bar", "x": "primary_bedtime_app", "series": ["sleep_latency_min__avg"], "title": "Average sleep latency (min) by primary bedtime app"}]} ```