How do you fix a sleep schedule that has drifted badly?

Anchor the wake time first and hold it, even after a bad night — this is the lever that eventually pulls bedtime earlier. Get bright light within thirty minutes of waking and dim lights in the evening. Do not go to bed early to compensate; you will lie awake and reinforce the association between bed and frustration. Move in 15 to 30 minute increments every few days rather than attempting a large jump. Avoid daytime naps beyond about twenty minutes while correcting. Expect a week or two of feeling worse before it settles, which is the part most people abandon.