It's 3 a.m., pitch dark, and you can't sleep. How can you survive the next day after being awake so long the night before? Difficulty sleeping is a common problem, but there are ways to escape it.

"Falling asleep is something passive and not forceable," said Cornelius Kellner, a sleep specialist. "If you offered someone 1 million euros to fall asleep in 10 minutes, he would not win the money."Limit your evening activities to a routine pattern, recommends Martin Muehlensiep of the sleep clinic at the University of Cologne. First read, then put on pajamas or a nightgown, then brush your teeth, for example.

"Each of these activities will become a signal to the body that it's going to go to bed soon," Muehlensiep said. But what should one do when that doesn't help? Constantly looking at the clock puts pressure on the body.

"When that happens, it's better to get out of bed and do a simple activity," Kellner said. Put pictures into an album or iron, for example, until fatigue sets in.

People who can't sleep often are those who brood or worry a lot. Kellner advises people who have difficulty sleeping to let their thoughts take them on a journey. "Place yourself consciously in a pleasant situation: on a beach or in a meadow. This can replace the worries at hand."