The last few minutes before falling asleep may seem like a small part of the day, but psychology suggests that the emotional state you carry into the night can interact with the way your brain processes memories. Sleep is not simply a period when the brain switches off. During sleep, recently learned information is reorganized and consolidated, helping some memories become more stable and easier to retrieve later. Emotional experiences can receive particular attention during this process, although researchers caution that the relationship is more complicated than simply saying a good mood creates good memories or a bad mood creates bad ones. Studies have found that sleep can strengthen emotional memories and alter how the brain processes them, while mood can also influence what people notice, encode and later retrieve.
This means that the emotional tone of an evening may be one piece of the larger memory picture, alongside what happened during the day, how strongly someone reacted to it and how well they slept.
