lack of sleep, or when you owe yourself some rest becasue you have been too busy.

when you are not getting enough sleep, and need to calculate how much you owe your body

sleep account is negative, or in the red

first used by British airways
and also sited on multiple occasions by lifehacker.com

Abbreviation for:

I DON’T GIVE A FUCK WHAT THE CDC SAYS YOU BE WEARING YOUR MASK

Something you accumulate whenever you don't sleep an adequate amount on a given night. In the ghetto they call it "slizzeep to da dizzebt".

The quantification of sleep debt.