One of the five stages of sleep, REM sleep usually starts about 90 minutes after you doze off.
Dreams during this stage are typically more vivid, fantastical, or even bizarre.
According to the Mayo Clinic, Lewy body dementia can lead to rapid eye movement (REM) sleep behaviour disorder, which means you start to physically act out vivid, often unpleasant dreams with vocal sounds and sudden movements.
Sabonaityte said: “These individuals may display similar actions while engaged in dreaming activities, like talking aloud in bed or making movements indicative of performing a task related to what they are dreaming about at the time.”