That sleep lasted little more than four hours, though.

His dreamless sleep lasted but a short while before the nightmares began.

My sleep had lasted only ten minutes or so.

Of course he had no way to grasp how long that sleep had lasted.

He has flopped into bed exhausted, knowing his sleep would last three hours.

Real restorative sleep never lasted long, no matter how tired they were.

His last sleep had lasted eight hours, and he had been conscious for less than a half hour.

They typically begin a few hours after sleep begins and can last from 15-180 min.

How long that sleep had lasted the survivors had never known.

His sleep had been heavy, but had only lasted about three quarters of an hour.