Is 90 Minutes the Magic Number When It Comes to Sleep?

According to some sleep experts, even if we go to bed at 1.30 am, we can feel rested if we set the alarm for 7.30 am or even at 6.00 am (dreamland forbid!)

BY KEEP UP KYLIE  |  26 July 2021

There are fewer feelings in this world that are worse than waking up from a dead sleep. I will be snoozing away mid-dream, and suddenly that alarm goes off as if someone has just fired a gun. There was so much more deep sleep to be had, and I just had the rug, er, mattress pulled out from underneath me. It does not matter if I had a solid eight hours prior to that grating alarm. I am tired even after eight hours of sleep. If I wake up from a sound sleep, it takes me hours until I feel like myself again. What gives?

Turns out there might just be a reason we feel so blasé when deep sleep is disrupted, and it is not a sketchy plan put into place by Starbucks to keep their coffee sales up. It may not even be from not enough sleep. When we sleep, we do so in 90 minutes cycles. The cycle starts out with about 65 minutes of normal sleep. We then experience about 20 minutes of rapid eye movement, also knowns as REM, sleep. After REM, we go back to normal sleep for about 5 minutes. That feeling of being awakened during the deepest part of the sleep cycle is what happens when that alarm sounds right in the middle of some quality REM sleep. The grogginess that sticks with us all day is the body’s way of saying it just did not get enough of that restful sleep known as REM.

This hardly seems fair! How can I control where I am in my sleep cycle if I require an alarm to wake up in the morning? Turns out I may be able to game the system and achieve restful sleep. Getting an amount of sleep that equates to three to five sleep cycles of 90 minutes may increase my chances of waking up well-rested and ready to face the day more so than sleeping for eight straight hours without completing a few full sleep cycles. That means that if I need to be awake by 8:00 am, I should get to bed by half past midnight or 2:o0 am (woohoo!) – but nowhere in between – so that I am sleeping in 90-minute multiples. That just may mean that my trip to Starbucks for coffee will be purely social instead of functional.

I get that this is easier said than done. Though I have the best of intentions when it comes to getting to sleep on time, sometimes it just doesn’t happen. Life gets in the way, chores need to be completed, and dinner may have happened later than I had planned. Even if I do happen to lay down at an appropriate bedtime, it may take a while to fall asleep.

Though the idea of a good sleep hack is intriguing, it is always good advice to make sure we get to bed at a decent hour and make time for restful sleep. Next, I’ll probably explore the 4-hour sleep cycle.