The hypnospectrogram: An EEG power spectrum based means to concurrently overview the macroscopic and microscopic architecture of human sleep

This study introduces a complementary tool for the description and evaluation of human sleep. The nocturnal sleep electroencephalographic (EEG) time–frequency analysis (TFA) plot (hypnospectrogram for short) is hereby proposed as a means to visualize both the macroscopic and the microscopic architecture of human sleep. It provides the ability to concurrently visually inspect the coarse sleep architecture, that is, the time-course of non-rapid eye movement (NREM) and REM stages, along with finer sleep elements such as slow and fast spindles, NREM delta distribution, REM alpha and beta, microarousals (MAs), and NREM cyclic alternating patterns (CAPs). Furthermore, the hypnospectrogram has the potential to provide visual quality of sleep (QoS) evaluation, as well as reveal the dominant rhythms and their transitions for every cerebral locus – as represented at the electrode space – during the night.