Why do you keep waking up at 3 a.m. — and how to fall back asleep

Is late-night tossing and turning stealing your shut-eye? You’re not alone.

Nearly one in five US adults struggle to stay asleep until sunrise — turning the dream of 8 hours of uninterrupted rest into a nightmare.

“Waking up in the middle of the night can be annoying, but this is not necessarily abnormal,” Dr. Dennis Auckley , director of the Center for Sleep Medicine at MetroHealth, told The Post. 3

In fact, it’s a nuisance that becomes more common with age. Sleep naturally gets lighter in our later years, leading to more frequent awakenings.

But experts say there’s a big difference between briefly waking up and lying wide-eyed for hours.

“It becomes a problem when an individual has problems falling back asleep, leading to what is known as sleep-maintenance insomnia (SMI),”