A new sleep calculator tells you when to go to bed to wake up fresh and energetic in the morning.

Hillarys has created the Sleep Calculator , an unusual calculator, claiming that "getting a good night's sleep is not about just going to bed early - it's about getting to bed and waking up on time. ".

Using a formula based on natural body rhythms, Sleep Calculator shows the best time to go to bed, depending on the time you want to wake up.

Experts claim that a sleep cycle lasts about 90 minutes and five or six cycles a night are ideal. Intermittent cycles can lead to fatigue the next day.

With this in mind, the Sleep Calculator says the key is not to go to bed early, but to plan when you sleep to ensure an uninterrupted 90-minute cycle.

For example, if you need to get up at 7 o'clock in the morning, you should go to bed at 21.46, 11.16, 12.46 or 2.16, Hillarys explains. This way you will wake up when a cycle ends and not in the middle of the cycle.

To calculate your schedule, click here .

Adapted from Euro Weekly News