this is how short-term -> long-term memory works. You build up 'competence; in the hippocampus during waking hours, and then when you sleep 'a part' of those memories are shifted into other areas of the brain so the hippo can be fresh for the next day. Caveats apply to things sometime take days, don't move, get erased etc. hippo is very capable so people can operate without sleep for quite a while but eventually overflowing this buffer/registry causes insanity/death. hilariously, your long-term appreciation of time is just the working set in hippo divided by the stored area in long term memory. thus as you get older time appears to go by faster in the aggregate. experience of simple in the moment phenomena is controlled elsewhere.