How to effortlessly improve your sleep (Sleeping in 90-Minute Multiples)

If you often feel groggy in the morning and tired throughout the day despite getting 7 or 8 hours of sleep, the problem might be your timing. The solution could be a simple sleep habit that will effortlessly improve your sleep by tomorrow.

What to do

Sleep in multiples of 90 minutes. Instead of 7 or 8 hours, go for 7.5 (or 6 or 9) hours of shut-eye per night.

Why it works

During the night, we go through different stages of sleep in cycles of 90 minutes. These stages notably include light sleep, rapid eye movement (REM) sleep and deep sleep. 

When woken up in the middle of one of these cycles, we experience what scientists call sleep inertia – a feeling of confusion and grogginess. Ever got woken up by a random sound in the middle of the night felt like you were hit by a bus? That’s what sleep inertia feels like.

Now, if you set your alarm so that you sleep for exactly 7 or 8 hours, you’re putting yourself at risk of suffering from sleep inertia in the morning. As a result, you might feel groggy and tired in the early hours – and even throughout the day.

How to do it

1) Start with your wake-up time. Ideally, you want to maintain that same wake-up time each day of the week, including weekends (here is why and how). For me, that’s 6 am.

2) Sleep in multiples of 90 minutes to avoid sleep inertia. For all of the benefits of deep sleep and REM sleep, go for five of these cycles (7.5 hours) on 80% of your nights. On shorter nights, go for at least four cycles (6.0 hours) no matter what. I opt for 7.5 hours most nights.

3) Take your wake-up time and subtract the number of hours you want to sleep. Also, add the time it takes you to fall asleep – usually, that’s 5 to 15 minutes. The result of this calculation is the time you should go to bed. For me, that’s 10.20 pm (06.00 am - 7.5 hours - 10 minutes).

That’s it. As simple as it sounds, sleeping in 90-minute multiples is one of the most powerful sleep habits. Try it and let me know how it goes.

And please share this post with one person that could also benefit from sleeping better without sleeping more:

Until next week,
Christian