You are not alone. I also have enough concentration to still work 16 hours straight - if I'm interested. At some point in time it degrades but that can be as late as 4 o'clock and then I'm screwed because my children (which also need less sleep than their age average) will wake me in any case. So my motivation to go to bed is much stronger than yours but nonetheless every now and then I will have to make do with 4.5 hours. Luckily my required average amount of sleep is 6,5 hours a day. I use multiple tricks mostly mentioned in other comments too: Red glasses at a fixed time (22:30) , schelling point at midnight, commitment to get up before 6:50 on the first ringing of the alarm (used simulation recently to make that work). All to varying degress of continuity (I form habits slowly). I guess you have to experiment, live with it or indeed use commitments. Partners can be strong motivator on this.