Revolutionizing Sleep Science: A Narrative Review of the Historical Origins and Current Applications of Sleep Neuroimaging

Abstract

Sleep neuroimaging is a subfield of sleep science that goes beyond polysomnography by combining neuroimaging techniques with validated sleep research methods to characterize sleep-wake states and investigate sleep-related processes across the 24-hour day. In this article, we review the historical advancements and applications that grew out of somnography leading to current sleep neuroimaging methods. We highlight the power of somnoimages to help visualize sleep research results and communicate complex information about sleep processes. We also suggest several ways in which applying neuroimaging during sleep has opened new avenues to more fully capture the nature of sleep, uncovered mechanisms of sleep-wake regulation, and increased understanding of sleep-related processes. Current applications and future directions of sleep neuroimaging are also discussed.

Keywords: EEG-fMRI; sleep fMRI; sleep neuroimaging; somnoimages; somnoimaging.

Figure 1

This figure is a timeline showing the major advancements made over the past 150 years in visualizing and communicating knowledge about sleep. This birds-eye view of the timeline shows the evolution of somnography into sleep neuroimaging moving from black and white somnochart and graphs, to colorful 3D somnoimages produced today. A description of each chart, graph, or image depicted in this timeline can be found in Table 1 corresponding by date. A description of each symbol in the figure is beyond the scope and purpose of this review.