Will my memory improve if I sleep more?
Getting enough sleep, and particularly the deep sleep phase, is an active part of how your brain retains new information. Too little sleep makes your memory not only weaker but also less reliable, so it pays to take your sleep seriously.
Deep sleep, also known as non-REM sleep, actively converts new memories into stable long-term storage. During this phase, the hippocampus (the brain's memory centre) replays the new information over and over, after which it is transferred to the cerebral cortex. This has been robustly demonstrated across multiple studies and is considered a necessary biological process, not a passive rest period.
Alongside deep sleep, dream sleep (REM sleep) likely contributes to a different aspect: linking new memories to things you already knew, and processing emotional experiences. The exact contribution of REM sleep is less well understood than that of deep sleep, but the evidence is reasonably convincing.
Sleep deprivation does not only weaken your memory, it also makes it less reliable. Research showed that both a single completely sleepless night and seven nights of only five hours of sleep increased the likelihood that people stored incorrect information as genuine memories. This applies to young adults as well as to adolescents.
A nuance that science has not yet fully resolved: memories are also consolidated while you are awake. Exactly how large the unique advantage of sleep is compared with quiet wakefulness remains an open question. That said, sleep plays a role that cannot be replaced by wakefulness alone.
Based on multiple reviews and experimental studies (PMID 34709916, 31451802, 40962324, 40875205, 30340875, 26447570, 27381857). The causal mechanism for deep sleep and memory consolidation is strongly supported; the precise contribution of REM sleep and the comparison with consolidation during wakefulness are still subjects of ongoing research.