What is the 3-3-3 rule for sleep?

The 3-3-3 rule helps you recognize whether poor sleep is heading toward insomnia. It applies if you sleep poorly at least three nights a week, this has already lasted three months, and it affects at least three aspects of your day (fatigue, concentration, mood, focus). If all three apply, discuss it with your doctor. There's also a wind-down variant (no intense exertion, no heavy meal, and no caffeine in the hours before bedtime), but the recognition rule is the one most commonly used.