1. Our bodies can rest when we sleep. 2. I've heard that our brain can clean itself. 3.We can memorize longer by sleeping. 4. An injured area can heal.

Hello, Henry!
These are all great ideas! Keep up the good work!
~Teacher Selene 

1. Our bodies can rest when we sleep.
>>CORRECT 
2. I've heard that our brain can clean itself.
>>CORRECT 
3.We can memorize longer by sleeping.
>>We can improve our memory by getting enough sleep. 
4. An injured area can heal.
>>Getting enough sleep can also help heal our wounds.