This podcast episode explores the various functions of sleep, including cleaning up waste products and repairing neurons, and how it affects memory formation and recall.
Scientists have not found any animal that does not need sleep, as all living beings require some amount of recovery, regenerative functions, and chemical rebalancing. However, some creatures with short lifespans such as flies may not need sleep as they do not live long enough to require recovery time.
The content of dreams can often be related to our experiences during the day, particularly stressful or traumatic ones, feeding into the theory that dreams are a way of processing and consolidating short-term memories into long-term ones.