An online sleep calculator can tell you exactly what time you should go to bed in order to wake up feeling refreshed — or so it claims.
Whether you’re scheduled to start work at 8am, or you’re looking to stay up a little later tonight but still want to feel bright and bubbly for tomorrow, Hillarys’ Sleep Calculator claims to offer the best times to let your head hit the pillow.
The calculator, used by UK home decor site Hillarys, says the trick to a refreshing 7am wake-up is not about more sleep, but when you sleep.
So, how does it work?
The calculator proposes bedtimes according to 90-minute sleep cycles. By the end of a sleep cycle, we enter into the last stage of REM (Rapid eye movement) sleep. Scientists have found people wake most refreshed when they wake from REM Sleep.
The calculator also factors in that most people take approximately 14 minutes to fall asleep.
After entering your wake-up time into the calculator, whether that be 7am or 10am, it will then give you a list of times that would suit you best to fall asleep.
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For example, if you’re wanting to wake up at 7am, the calculator advises that you’re best to nod off at 9:46pm, 11:16pm, 12:46 am or for extreme night owls, 2:16am.
The calculator also gives you the chance to try things in reverse. If you’re wanting to nap or fall asleep right now, it can calculate the best times to wake up.
If you were to fall asleep at exactly 3:40pm in the afternoon, the sleep calculator proposes that 5:24pm, 6:54pm, 8:24pm or 9:54pm are the best times to wake up.
Should I trust it?
The calculator isn’t endorsed by Australia’s Sleep Health Foundation.
The Sleep Health Foundation says the calculator “massively over-generalises” the concept of sleep cycles and the idea that waking from REM sleep will make you feel more refreshed.
By assuming sleep cycles last 90 minutes, the calculator fails to acknowledge the importance of a good sleep routine, over tricking your body into sleep.
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“There are lots of individual differences in cycle length and the variation may be from around 60 to 110 minutes. There may also be unpredictable differences in the same individual from night-to- night,” the Foundation writes on its website.
While the calculator might work as a guide, the Foundations urges the best trick for waking up refreshed in the morning is by following routine and regular sleep habits.
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