The cognitive purpose of sleep is an open question. Recently, however, scientists have a new conjecture (“How memory replay in sleep boosts creative problem solving“) as to the purpose of two important phases of sleep.

According to the research, the brain goes through several 90-minute cycles of REM and Non-REM sleep. Non-REM sleep involves the sequential replay of acquired memories. In contrast, REM sleep involves a more random associate game involving disparate memories. In deep learning, this is analogous to the search algorithms of optimization and exploration respectively. Read More