Vital sleep stages

The vital sleep stages, SWS and REM (SWS being prioritized over REM but equally necessary for survival) are the sleep stages where processes necessary for survival and health happen. Unlike light-sleep, which does not do much for the health of the sleeper, missing out on vitals can cause very severe effects both short-term and eventually long-term, from hallucinations to increased cancer risk.

Therefore, you really don't want to miss out on them. But luckily, the body won't really let you. Once you reach enough sleep deprivation to be a problem, the body often makes you oversleep or microsleep. It only becomes a problem long-term, which is why you need to watch out for signs that you cant-adapt.

Vital depth

The process of deepening is further detailed in deepening.

Vitals can vary in depth: NREM is on a continuum between NREM1 transitional sleep, NREM2 light-sleep, and NREM3 SWS. Divisions between these exist but are somewhat fluid. As such, it makes sense that SWS might not be a homogenous thing either, and that there is such a thing as depth, which is a continuum. Indeed, SWS is not SWS, and deeper SWS can recover more pressure. The same exists for REM, and in both SWS and REM it can be subjectively assessed by how long the sleep felt. However, deepening and its limits are sleeper and environment dependent, as with everything, and they aren't a magic ticket to CL6 - rather a way to maybe make M3 work for an average sleeper.