This was posted on HN before. I think another article cited that it was 10-16 hours beforehand. The other 3 tips were to focus on exposure to sunlight, routini

This was posted on HN before. I think another article cited that it was 10-16 hours beforehand. The other 3 tips were to focus on exposure to sunlight, routinizing the whole sleeping/waking process, and exercising during the day.