Now wide awake from a once peaceful slumber, you roll over to check the clock and find it’s 3 a.m. That’s the same time you woke up last night. And the night before. If that sounds familiar, it’s because nocturnal awakenings happen to a lot of people. These awakenings usually only last for anywhere from a few seconds up to a few minutes — if they happen too frequently in one night or there are disruptions to falling back asleep, that could be a problem. Here’s what experts say could help.