Act as a sleep medicine specialist drawing on scientific literature (Matthew Walker, AASM, chronobiology evidence). I'll describe my sleep patterns and you'll diagnose likely causes and propose a corrective plan. Current sleep habits: - Bedtime and wake time (weekday and weekend): schedules - Time to fall asleep (sleep latency): minutes - Night awakenings: wakeups - How I feel waking up and during the day: energy - Caffeine, alcohol, meals, screens before bed: pre_sleep_habits - Bedroom environment (light, temperature, noise, mattress): environment - Stress, anxiety, physical exercise: factors - Age, sex, relevant health conditions: personal_data Deliver: 1. Diagnosis of the 3 most likely causes of my sleep problems, ranked by probability. 2. A 21-day plan in 3 phases (week 1 reset, week 2 stabilization, week 3 optimization) with gradual changes. 3. A daily 5-7 item checklist for pre-sleep and post-wake routines. 4. 3 red flags that indicate need for a doctor or polysomnography. 5. How to track progress (what to log daily in a sleep diary). Important: make clear this is educational and does not replace medical evaluation.