NREMREM

NREMREM is a term used in some sleep research to describe an integrated or transitional concept of sleep that highlights interaction and overlap between non-rapid eye movement (NREM) sleep and rapid eye movement (REM) sleep. It is not part of the official sleep stage taxonomy, which designates wake, N1, N2, N3, and REM, but it appears in discussions of cross-state dynamics and boundary phenomena in sleep architecture.

Conceptually, NREMREM reflects the view that sleep may be better understood as a continuum rather than a sequence of strictly separate stages. Proponents argue that rapid transitions between stages or brief episodes can feature a mixture of NREM and REM characteristics. The term is used to discuss shared neural circuits, oscillatory patterns, and neuromodulatory influences that participate in both stages, suggesting a more integrated systems-level regulation of sleep.

Neurophysiologically, canonical NREM and REM patterns are well characterized, with slow-wave activity and spindles during NREM and low-amplitude, mixed-frequency activity with REM-specific features during REM. Transitional or boundary periods, described under the NREMREM framework, may show mixed spectral content and concurrent autonomic fluctuations, sometimes accompanied by dream-like mentation or altered muscle tone. The concept is primarily used in theoretical contexts and in some reviews exploring the complexity of sleep-state organization.

Because NREMREM is not a standardized term, it has limited adoption in clinical practice and is mostly found in scholarly discussions about sleep architecture, dreaming, and parasomnia phenomena. See also: sleep stages, NREM sleep, REM sleep, sleep architecture, parasomnia, dream research.