Loop memories, sometimes referred to as in-loop memories, are a common occurance in the loops where, upon Awakening, loopers are able to retain any memories their unawake selves had. It's incredibly useful for figuring out what the looper's 'role' for that loop is, and can often let the loopers gain skills they wouldn't normally possess thanks to their unawake selves practicing them. The exact extent of this is unknown, as no one is fully sure if learning these abilities while Awake allows for better mastery or not.
An in-loop reflex is an extension of loop memories, as in any 'tics' or 'quirks' their unawake selves had will occasionally force their way through to their Awake selves. For example: If there's a paticularly tragic or traumatizing event in a looper's loop memories, despite not going through it themselves, any mere mention or reference to said event will cause them to flinch. This seems to be a 'one loop only' thing though, as when a looper manages to return to their base loop they no longer seem to possess this problem.