Complex nocturnal behaviors are some of the most fascinating sleep disorders in medical practice and often include a variety of conditions that require detective work. Parasomnias can include both simple and complex abnormal behaviors and are defined as abnormal sensory or behavioral phenomena that manifest during sleep-wake transition. Parasomnias are divided into those that occur during rapid eye movement (REM) sleep (including nightmares, isolated sleep paralysis, and REM sleep behavior disorder or RBD) and those occurring during nonrapid eye movement (NREM) sleep (such as sleepwalking, sleep terrors, and confusion on arousal. RBD often precedes the onset of neurodegenerative conditions, particularly α-synucleinopathies, a group of neurodegenerative diseases characterized by abnormal accumulation of insoluble α-synuclein in neurons and glial cells, comprising Parkinson’s disease, dementia with Lewy bodies, and multiple system atrophy. Other forms of complex behaviors include motor behaviors of sleep, such as rhythmic movements disorder, periodic leg moments of sleep, and bruxism. Sleep related epilepsy may resemble parasomnias but tend to be monomorphic and stereotyped. The lecture will provide insight into the differential diagnosis using video examples covering the unique features of the key parasomnias, their unique features, and management strategies.