What sleep debt is, and what it is not.

Sleep debt is a useful piece of shorthand rather than a precise ledger. It describes the gap between the sleep you needed and the sleep you got, and it accumulates quietly across a run of short nights.

A long weekend helps, but it does not settle the account. What tends to help more is anything that makes the next night easier to fall into, which is part of why the evening class finishes early enough to leave the rest of the night alone.