If you keep late hours, you’re more likely to suffer from insomnia than someone who gets to bed earlier, according to Stanford University researchers. Investigators asked 312 men and women about their sleep preferences and divided them into morning people, night owls or intermediate types who fell in between. Study participants kept weeklong sleep logs—noting bedtimes, number of awakenings, time spent out of bed during sleep time, sleep quality, total hours asleep and any sleep-aid drugs they took. Compared to the other two groups, night owls spent more time out of bed and experienced more overall sleeplessness. They also had more erratic bedtime and wake-time habits and were more depressed and frustrated by their inability to sleep.