State dependent learning is a basic human filing strategy -- we all do it. You may recall (or not, depending on your state) the study that found that students who studied while stoned scored better on tests when they were stoned than if they weren't stoned, and I think conversely for those who studied straight. Recall is easiest from the state in which the experience was stored.

Its much more salient a matter in DID.

If one can rule out alcohol/drugs and organic problems like temporal lobe epilepsy, then lost time is a possible indicator of a dissociative disorder, one of which is DID.

In DID, the separation is distinct, but not necessarily extreme. There may not be separate names and wardrobes. It may be entirely covert.