Time to Wake Up!

Pietari Nurmi
Jul 15 · 3 min read

Your body is a powerful and exact instrument that is very precise in knowing when it is the best time for you to wake up. However, there is not much use to even the most accurate clock if it’s set to a wrong time.

The same processes responsible for falling asleep also make you wake you up. They are sleep pressure and the internal clock. The level of sleep pressure keeps decreasing when you are sleeping, and your body wakes you up when it has been asleep for long enough. The inner clock, on the other hand, raises your alertness in the morning no matter how much sleep you’ve had. If these two rhythms are not aligned, your body won’t work optimally. For example, if you go to bed later than usual, your inner clock might wake you up too early the next morning, even if you didn’t get enough sleep yet.

Sleep pressure and internal clock work together
The amount of sleep pressure (blue line) increases when you are awake and decreases during sleep. The level of alertness determined by the internal clock (orange line) is more consistent and follows the time of the day the amount of light in the environment. When both of these rhythms are in sync you wake up refreshed and get tired not until the evening.

Waking Up Naturally

The inner clock and decreasing sleep pressure together set your natural wake-up time for each morning. Waking up during that time happens effortlessly, and you’ll feel well-rested. Convenient, right? But why do so few of us wake up according to our natural rhythms?

Going to sleep is simple (at least in theory): you have complete freedom over what time you will go to bed. In the morning, on the other hand, it is someone or something else that gets to choose your wake-up time. Most of us have to go to work, school, or engage in other daily duties. For that reason, we invented alarm clocks that forcefully wake us up at a specific time. If your natural wake-up time is not at hand when the alarm goes off, waking up is harsh, and you’ll feel tired in the morning. Still, you have to force yourself up to work. Does this sound familiar? For the sake of your own well-being, the best solution is to try to shift your sleep-wake rhythm to earlier. By going to bed sooner, your natural wake-up time gets closer to the time you actually have to get up, and you will wake up feeling refreshed and ready for the day!

Habits From This Lesson

Additional Reading

Borbély, A. A., Daan, S., Wirz-Justice, A., & Deboer, T. (2016). The two-process model of sleep regulation: A reappraisal. Journal of Sleep Research, 25(2), 131–143.

Walker, M. (2017). Why we sleep: Unlocking the power of sleep and dreams. Simon and Schuster.