Want to wake up feeling fresh? Try this sleep calculator which tells you the PERFECT time to hit the sack

Do you ever wake up feeling groggy?

Well, starting the day feeling fresh and alert is all about timing.

By inputting when you need to wake up, this sleep calculator will give you the perfect time to hit the sack.

Or, if you’re thinking about taking a nap right about now, it will tell you when to set your alarm for.

MAILONLINE APP USERS CAN USE THE TOOL BY CLICKING HERE 

The calculator, by home interiors specialist Hillarys, uses a formula based on the body’s natural rhythms. 

According to the NHS, adults need seven to nine hours of sleep a night — which works out as five or six 90-minute cycles.

Being woken by an alarm in the middle of one of the cycles is often what makes getting out of bed feel like such a challenge, as you could be interrupting deep sleep, according to the Sleep Council.

There are different phases of each sleep cycle, starting with three stages of non-rapid eye movement sleep (NREM) which get progressively deeper, followed by a fourth phase of rapid-eye movement sleep (REM), which is when we are in a deep enough sleep to dream.

If you are woken during REM sleep you may feel tired for the rest of the day, so it is best to wake between cycles. 

For example, if you need to wake up at 6.30am, the calculator will tell you to head to bed at 9.16pm, 10.46pm, 12.16am or 1.46am. 

When calculating your shut-eye schedule, it factors in that most people take around 14 minutes to nod off.

While adults need between seven and nine hours of sleep, children need between nine and 13.

And babies and toddlers generally need between 12 and 17 hours of sleep everyday, which the NHS says is essential so they can develop and process the new experiences and skills they are learning.

The amount children need to sleep drops steadily as they grow older, with toddlers needing 12-14 hours but 12 to 18 year-olds needing just eight to nine. 

This means parents can put their children to bed at 7.46pm and have three hours to themselves before getting an optimal amount of sleep.

If you need to wake up at 6.30am, the calculator will tell you to head to bed at 9.16pm, 10.46pm, 12.16am or 1.46am

Yvonne Keal, senior product manager at hillarys.co.uk, told MailOnline: ‘We all know how important getting a great night’s sleep is. 

‘It can improve concentration, reduce stress levels and even keep our hearts healthy. 

‘Yet according to a YouGov data tracker, a staggering 78 per cent of Brits fail to get the recommended eight hours of shut-eye every night. 

‘Modern “always-on” lifestyles and busy home environments can actively prevent us from getting the rest we need.’