Some people, even when they know they have to wake up at a certain time, struggle to get their body clocks in gear. Luckily for them, a new website has a calculator that tells you when to wake up between sleep cycles.

All sleepyheads need to do is enter their waking up time in the calculator at and it will tell them when to go to bed, and when to wake up between sleep cycles.

For example, if you want to wake up at 8:00 am, then the calculator advises you to go to bed at 11:00 pm, then wake up for a few minutes at 12:30 am, then 2:00 am, then 3:30 am , before rising as planned at 8:00 am.

How does this work?

The theory on which the calculator works is that a typical sleep cycle lasts 90 minutes. By waking up briefly between cycles, you will wake up in the morning feeling refreshed instead of groggy and tired.

A conventional alarm clock is designed to only wake you up at a fixed time, so to implement this strategy practically, you would need to reset your alarm each time it woke you up. A better way is to use the Sleepy Time app, which is available for Android and iPhones. This app does the calculations then sounds the alarms to wake you up between sleep cycles.

But should I be waking up several times in the night?

Yes, according to sleep psychologist Gregg Jacobs, who explains that this is part of “normal human physiology”.

He is against the idea of only sleeping in solid blocks of six to eight hour, and argues that our ancient ancestors woke up a few times in the night and that this was a way to naturally regulate stress.

Though there have been no definitive scientific studies to support waking between sleep cycles, people who have tried the system say that it works.

No matter what sleep pattern you follow, sleeping on a luxury orthopedic or king size pocket spring mattress can only improve your sleep quality.