You might look forward to sleeping in on the weekend, especially after a busy week. However, there’s a limit to catching up on sleep. Some hours will be lost forever.
In some ways, sleep is like food. Starve yourself of its nourishment and your body will feast on it when next given the chance, refilling drained reserves.
After a night or two of poor rest, we will naturally sleep longer on subsequent nights. We accumulate a “sleep debt” that we carry until we can get decent shut-eye. Powerfully restorative to body and mind, it is slow-wave sleep that your body craves most when you’ve been burning the candle at both ends. In catch-up sleep, more time is spent in the slow-wave stage, so you will experience fewer exciting dreams.
Unfortunately, the body can’t fully recoup lost sleep, but that’s not to say you shouldn’t catch up on as much as you can. No matter how big the debt, you can normally manage only two or three extra hours over and above your normal nightly total, so sleeping in on the weekend can only claw back so much lost time. The “interest” you pay on sleep debt is poor long-term health, so it’s vital to keep your sleep hours in the black as often as you can.