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Here's why you feel even more tired after your night out

You feel like you sleep well, yet you often wake up groggy and getting out of bed becomes a real ordeal. You may be suffering from sleep inertia. Explanations.

What is sleep inertia?

Sleep inertia, or sleep drunkenness, is characterized by a state of drowsiness after waking up. The impression of being in a thick fog, of having barely slept. That your brain and your body are still sleeping while you are awake.

This transition period between sleep and wakefulness can last from fifteen minutes to more than an hour, depending on the person. It is complicated because it can induce a decrease in alertness. A problem when you are a young parent, in particular. One can also suffer from irritability, bad mood or even states of depression.

Voici pourquoi vous avez l’impression d’être encore plus fatigué après votre nuit

Don't worry, it's not a pathology. Sleep inertia is a natural phenomenon. It's more about your sleep cycles. Indeed, this phenomenon would be linked to the phase of sleep that was interrupted. However, it should not be ignored: remember, sleep is very important for the proper functioning of our body.

Vous vous réveillez chaque nuit à la même heure ? Voilà ce que ça veut dire !

Sleep inertia: knowing the sleep cycles

Sleep corresponds to a succession of 3 to 6 cycles. A cycle can last between 60 and 120 minutes, with an average of 90 minutes. During this cycle, you go through different phases:

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Note that the rhythm of sleep is not fixed, as explained by Inserm. It varies during the same night: the first cycles of sleep are generally made up of slow and deep sleep, while the second part of the night is essentially characterized by light and paradoxical sleep. Besides, every night, whether you are a heavy sleeper or not, we all wake up for a few moments, without remembering it the next day.

How are these cycles related to sleep inertia? Because this phenomenon occurs when you wake up during a cycle, and especially during the deep sleep phase. Several scientific studies have shown that an individual's brain performance can be drastically reduced if the deep sleep phase is interrupted. Hence the state of drowsiness and loss of bearings that can result from the inertia of sleep.

How to avoid sleep inertia?

Sleep being made up of several cycles, it is necessary to go to the end of these to sleep well and for the night to be restorative. Thus, when you program an alarm, it must be avoided that it rings in the middle of a cycle, and even less during the deep sleep phase.

Taking into account that a cycle lasts on average 90 minutes, and that it takes 3 to 6 cycles to wake up in good shape, you can therefore easily calculate at what time you have to go to sleep and get up to avoid this inertia of the sleep. It should also be kept in mind that the average duration of falling asleep is about 20 minutes. If this calculation seems complicated to you, rest assured, some online sites offer to do it for you, depending on the time you want to wake up or go to bed. For example, if I want to get up at 8 a.m., I have to fall asleep at 11 p.m. to have 6 cycles and 9 hours of sleep, or at 12:30 a.m. to have 5 cycles and 7.5 hours of sleep.

When you are subject to sleep inertia, you must also avoid sudden awakenings. You can use a dawn simulator to wake up gently. Or sleep with the shutters and curtains open, to let the light in (which is a little more complicated with winter time). The light will reduce (or even stop) the secretion of melatonin, which promotes falling asleep and maintaining sleep.

Finally, if you suffer from sleep inertia, sprinkle yourself with fresh water as soon as you wake up and take your dose of caffeine. This should help you see things more clearly.