Hi there,and welcome to BYC!
The heat lamp needs to stay on all day 24/7. You don't turn it off, unless the temp of your house is hotter than the brooder temp. Chicks sleep a lot. They should be sleeping thru the entire night at this point. Great that you are using a red bulb. Red has good qualities and is not an exciting type light. It also allows for a normal sleeping pattern at night.
Great to have you aboard and enjoy BYC!
A big X2
