Instead of having you friend stay up all night. You can both wake up after 6 hours of sleep. And then you go back to sleep and he will stay up. After 6 hours of sleep you enter into you 4th dream period which last 30-60 mins. I think that it would be more productive to try this method then, because it is a longer dream period and your friend won't fall asleep on you if you only ask him to stay awake for 60 minutes instead of 6 hours.