Our body knows exactly what’s good for it, so instead of waiting for a startling noise, they wake up before the alarm goes off.
You’ve probably set your alarm, but woken up before it rings. Now it turns out that this is no coincidence.
It may seem surprising, but our bodies can sense the time even when we are fast asleep. The circadian rhythm is controlled and synchronized by a mechanism of the central nervous system, which is based in the nucleus above the optic nerve junction in the hypothalamus, called the nucleus suprachiasmaticus. This nucleus can also decide when we are sleepy or awake.
If we consistently go to bed and get up at roughly the same time every day, our body adapts to this routine. A protein called PER, which regulates the sleep-wake cycle, plays a key role in this effect. Protein levels vary throughout the day, peaking in the evening and being the lowest at night. Low levels of PER protein also cause low blood pressure, which makes us sleepy.
With a consistent sleep schedule, our body learns to increase PER protein levels in time to wake us up before the alarm goes off. This is good not only because we don’t miss work or school, but also because waking up is stressful and our body is trying to protect itself from shock.