Biology
What allows animals to sleep without waking up?
Quick fact
Some dolphins sleep with half their brain awake, while birds can sleep during migration.
Why this is interesting
Sleep seems risky, yet almost every animal has evolved some form of rest.
Read the full explanation
Understanding What allows animals to sleep without waking up?
Sleep helps maintain brain function, energy balance, and survival.
A deeper explanation
The evolution of sleep reveals how animals balance the need for recovery with the dangers of being vulnerable.