I don't really know how to do it, except that there's a kind of switch in my brain, the same switch that I would tell, "I want to wake up at exactly 7:30am tomorrow" and have it happen, that can help sometimes. It seems to be a thought trick of some sort, telling your unconscious brain that something's important, and having it actually believe you. It might work for temperature too.
I have a switch on my alarm clock that does that. I have a switch in my brain which my brain uses to wake up just enough to get out of bed, turn off the alarm clock, crawl back into bed and go back to sleep. Actually, it's less of a switch and more of an involuntary automated response that's highly resistant to attempts to circumvent it; I've tried putting the alarm clock in awkward places and piling things on top of it, but I can do quite complex things without waking up enough to be able to voluntarily stay awake, and I get back to sleep in seconds after even quite prolonged periods of being awake if I'm still tired, though if I've been awake for 30 minutes or so before I go back to sleep, I tend to drift between dreaming and being semi-aware of what's going on around me, things I have to do that day and so on.
It can lead so some odd thoughts when the two get mixed up, like thinking it's ok to keep sleeping because if I miss school/uni, I can just reload from an earlier save. It helps if I have something reasonably important to do on any given day, since then I get an 'oh shit!' squirt of adrenaline when I remember it, and that gets me up fairly quickly, though quite a few times when I've been really tired, I've gone back to sleep after having a shower and getting dressed.
