Our Creator, Allah, the Almighty, informs us in the Qur’an: “And We made your sleep [a means for] rest. And We made the night as clothing. And We made the day for livelihood” (Surat An-Naba’ 78:9-10-11).
When we have been awake for a long period of time, sleep/wake homeostasis tells us that a need for sleep is accumulating and that it is time to sleep.
It also helps us maintain enough sleep throughout the night to make up for the hours of being awake.
In the following video from TedEd in 2015, Dr. Shai Marcu defends early sleeping, showing how sleep restructures your brain in a way that’s crucial for how our memory works.