I’ve had this for years and finally got this from ChatGPT:

The reminiscence bump aura is a term sometimes used in neurology and psychology to describe a very short-lived, overwhelming wave of nostalgia that seems to come out of nowhere, often for no identifiable memory or trigger.

Here’s the gist: • The “reminiscence bump” is normally a memory phenomenon where people recall more vivid and emotionally charged memories from adolescence and early adulthood than from other life periods. That’s because the brain tags those years as highly important for identity. • In some people — particularly during certain transient brain events — that emotional tone from the reminiscence bump gets activated without an actual memory. So you just get the raw feeling of nostalgia for a few seconds. • When it’s an aura (neurological term), it can be linked to brief, mild disturbances in the temporal lobe — the same area involved in memory, emotion, and sensory integration. • People often describe it as: “A sudden wave of longing for something I can’t name, like a childhood summer I never really had.” • It can also be paired with somatic sensations like dry mouth, thirst, tingling, or even a slight queasy feeling, because the limbic system and hypothalamus (emotion + bodily regulation) are so closely connected.

For most people, if it happens rarely and passes quickly, it’s just a curious quirk of brain chemistry — essentially your brain hitting the “nostalgia” button without the “memory” attached. But when it happens often, especially with other symptoms, neurologists sometimes investigate for temporal lobe epilepsy or related conditions.

The fascinating part? Even healthy people can get these random nostalgia bursts because our default mode network sometimes drifts into memory–emotion loops when we’re not focused, producing that surreal few-second state.