What if I get in bed at 11 and just lie there?
Then 11pm is currently too early for your body clock, and forcing it teaches you to associate bed with frustration. Go back one 15-minute step, hold it for a week, and put the effort into morning light instead.
Can I catch up on the weekend?
Sleeping in past your fixed wake time by more than an hour undoes most of the week's shift — it's the same as flying two time zones west every Saturday. If you're wrecked, nap for 20 minutes before 3pm instead.
Does this work if I have insomnia?
This is a habit plan for people whose bedtime has drifted, not a treatment. If you're regularly awake for an hour or more, waking through the night, or exhausted after a full night's sleep, that's a conversation for a doctor — insomnia and sleep apnea both have real treatments and neither responds to willpower.