Changes in neurovascular dynamics were examined in head-fixed mice (left) which were awake (grey), in non-rapid eye movement sleep (NREM; blue), and rapid eye movement sleep (REM; red). (A) As inferred from changes in cortical hemoglobin levels, total blood volume increases drastically during sleep, especially during REM sleep. (B) Average arteriole dilation during sleep increases above the level found during the awake state. (C) Sleep occurs during eyes-open behavioral rest in head-fixed mice. NREM sleep (38% of rest periods) commonly occurred during behavioral rest. REM sleep was less common but still occurred (5% of rest periods). (D) The strength of coupling between neural signals (multi-unit activity, or MUA) and levels of cortical hemoglobin (HbT) increased during NREM sleep, and the timing of coupling shifted across sleep stages.
Image credit: Mouse illustrations adapted from Luigi Petrucco via SciDraw (CCBY 4.0); Blood cells illustrations adapted from John Chilton via SciDraw (CCBY 4.0); Panel C adapted from Turner et al., 2020 (CCBY 4.0).