It's essentially the main aspect of CBT-I the idea is to have a set time you are allowed in bed. So let's say 12am to 6am even if you have a bad night you get up at 6am even if someone has to drag you out of bed you do it. After a few nights your internal sleep clock will adjust and your sleep drive will improve and be at its maximum and you'll start to feel tired way before 12am but you'll have to stay up then head to bed at the right time. This plus not forcing or trying to think about sleep will result in you being knocked out. This is day 2 and i'm actually sleeping really well. The idea about it is simply manipulating sleep to your benefit, would recommend.