So next time you can't fall asleep, take off the blankets, make sure your room is cold, and then get really, uncomfortably cold, and stay that way for at least 15 minutes. Then, and this is key, cover your whole body only with your sheet, and then pull the blanket just over your legs. You'll warm up and fall asleep. If you pull the blanket all over yourself and "mummify", then you'll risk getting too warm, which will wake you right up again.
I'm sure this doesn't work for everyone, but I think many people get too warm and comfortable, and that will keep you awake.
Get cold, warm up, and snooze!