Along with more meditation comes less need for sleep. Whereas I’d typically require a solid eight hours, because I’m now diligently, formally meditating every morning and cultivating more and more mindfulness in my daily life off the cushion, I find that I only need four to six hours to feel re-energized.
Last night, however, I was awoken and couldn’t get back to sleep the rest of the night. I futilely tried to rest awhile and then surrendered to wakefulness and checked my email. I tried to sleep again, then got up, wrote, sat in meditation, then tried to sleep again. I feel marginally rested, thanks to something I learned at my first Vipassana course in Texas in 2007.
According to S.N. Goenka, teacher of Vipassana meditation (those nutty ten-day silent meditation courses):
Vipassana helps you. When a Vipassana student can’t sleep properly, if he or she lies down and observes respiration or sensations, sound sleep comes. Even if they don’t get sound sleep, the next day they will get up feeling very fresh, as if they have come out of a deep sleep. Practice Vipassana even when lying down. Try, and you will find that it is very helpful.
This simple advice has helped me immeasurably. Though I usually fall asleep easily and sleep well, pre-Vipassana, when sleep would evade me, I tended to turn into a big baby. Anxiety and irrational thoughts would swirl through my mind. I’d toss and turn and toss some more. But now, I remain relatively relaxed and try to appreciate rest, even if it’s not REM.
Another yogic tip for restlessness/sleeplessness: breathe through your left nostril 
only. Close off the right nostril and breathe long, slow, deep breaths for several minutes through the left side. This helps calm the mind and can induce relaxation, if not actual sleep.
Last but not least — when in doubt, take a nap!
