Dreams

Dreams are sequences of images, ideas, and emotions that typically occur during sleep. While most dreams happen during rapid eye movement (REM) sleep, some can occur during non-REM stages. People vary markedly in dream frequency and in how much of a dream they remember upon waking.

REM sleep is characterized by heightened brain activity, intense emotions, and vivid and bizarre content. Dreams can last for a few minutes or longer, with successive REM periods extending through the night. Dream content often draws on memories, daily experiences, fears, and aspirations, and recall is influenced by waking state and attention to sleep.

The study of dreams draws on psychology and neuroscience. Theories about dreaming include Freud's idea that dreams reveal wishes, cognitive approaches that view dreams as reflections of memory processing and emotional regulation, and the activation-synthesis theory, which posits that dreams are the brain's attempt to interpret random neural activity during sleep. Some researchers propose threat simulation and problem-solving functions, though consensus remains limited.

Research methods include polysomnography to monitor brain activity during sleep and structured dream reports. Neuroimaging shows REM sleep involves limbic regions and reduced prefrontal activity, which may underlie the less inhibited, more emotional quality of dreams.

Clinically, dreams are associated with several sleep phenomena. Nightmares and nightmare disorder involve repeatedly disturbing dreams leading to distress or impairment. REM sleep behavior disorder includes acting out dreams physically. Treatments such as imagery rehearsal therapy and cognitive behavioral approaches are used for nightmares; pharmacological influences on REM can alter dreaming patterns.