I've been trying a biphasic sleep schedule on and off for a couple of weeks now. Instead of the normal 8 hours per night, I sleep 6 hours each night and take a long nap in the afternoon. I have a wakeup lamp to wake me up after the night's sleep, and wake up naturally from the nap, generally after something between one and two hours.

A couple of rebound effects I get from trying to reschedule a full night's sleep is that going to sleep much earlier than what I'm currently used to makes me wake up after a couple of hours and stay up the rest of the night, and sleeping less than usual on two consecutive nights is hard to do. Doing the biphasic thing and taking a nap every day fixes both these problems. I'm no longer trying to get to sleep early enough that my body thinks it's only having a late nap, and the naps counterbalance the sleep deprivation from sleeping less than usual at night.

The routine got messed up when I started running this spring and got my leg muscles sore from a lack of training. My body likes a full night's sleep a lot more when there's a bunch of damaged tissue to heal, so I didn't manage to keep waking up after only six hours of sleep any more.