Many people wake up feeling groggy and spend the day counting the hours until they can climb back into bed.
Sometimes it doesn’t seem to matter if you get the recommended seven or eight hours, the next day can still feel like a struggle as you battle lethargy.
But Dr Karan Raj has shared a video on TikTok to explain that it might come down to waking up in the middle of a sleep cycle rather than simply not getting enough shut eye.
The doctor, who racks up millions of views by sharing his expert knowledge on everything from food to medical advice, posted a video titled ’90 minute rule’ to demonstrate how to calculate your perfect time to go to bed.
He explained: “Try this if you want to wake up feeling refreshed.”
“Every night your brain moves through several sleep cycles. Each cycle starts with light sleep, then you enter deep sleep, then dream, and back to light.
“Each of these cycles is around 90 minutes. You feel most refreshed if you wake up at the end of one of these 90 minute cycles.
“That’s because you’re closest to your normal waking state and to increase the chances of this, first figure out what time you want to wake up.”
Dr Raj says that if you plan to wake up at 8am, you should work backwards in 90 minute periods until you reach the time closest to when you want to go to bed.
So if you go to bed at 11pm, you should wake up right at the end of your sixth cycle feeling ready to take on the day.
He added: “Won’t work for every single person because of fluctuations in the length of our sleep cycles but it’s a good rough target to aim for!”
The video racked up more than one million views as one person commented to say: “This works, tried it last night.”
And another joked: “Thing is, I’ll be in bed like ‘I have seven minutes to fall asleep to be at the end of a cycle’. Then stress about that so much I don’t fall asleep.”
Do you have any sleeping tips? Let us know in the comments.