let’s us take a look at the prophet’s daily schedule
He used to wake up before dawn ( 3 am )
And stay awake until noon ( 12 pm )
At noon he takes a nap and wakes up before the evening 3 pm
Lastly he sleeps right after isha prayer the last prayer of the day which is 8 pm
All his sleep wake cycle are aligned with Islam 5 prayer times , which are dependent on the sun’s positions to the earth
Let’s look at what science says about circadian rhythm. There are 2 Main hormones responsible for our wake and sleep states, cortisol and melatonin.
As you can see in the graph cortisol the wake hormone starts to rise at 3 am.. which is exactly when the prophet used to wake up.
Then it dips very strongly at 12 pm which is when he used to take his nap ( this nap is also sunnah which means it’s recommended strongly for all muslims)
Lastly melatonin started to rise at 6 pm and is at its highest 9 pm ( melatonin is responsible for detoxification)
So the prophet sleeps directly after Isha prayer so he doesnt miss out on its benefits