# Cerebral and Peripheral Hemodynamics Across Wakefulness and NREM Sleep

## TL;DR

This study explores how blood flow in the brain and fingers changes during wakefulness and NREM sleep, finding significant differences and desynchronization during deep sleep.

## Contribution

The study reveals distinct cerebral and peripheral hemodynamic patterns and their desynchronized coupling during NREM3 sleep.

## Key findings

- Cerebral and peripheral hemodynamics show marked differences in oscillation amplitude and spectral power during sleep.
- Low-frequency coupling between cerebral and peripheral hemodynamics desynchronizes during NREM3 sleep.
- NREM3 sleep appears to play a key role in restoring cerebral vasomotion.

## Abstract

Wake/sleep‐related changes in cerebral hemodynamic oscillations are well established, but similar changes in peripheral hemodynamics remain largely understudied. Moreover, how the relationship between cerebral and peripheral hemodynamics varies across sleep–wake states is not well understood, despite evidence that these oscillations in the low‐frequency range are strongly coupled during wakefulness. In this study, we investigated the temporal and spectral characteristics of cerebral and peripheral hemodynamics, as well as their low‐frequency coupling, across sleep and wake states. To this end, we simultaneously measured cerebral hemodynamics using functional magnetic resonance imaging (fMRI) of the brain and peripheral hemodynamics using near‐infrared spectroscopy (NIRS) of the fingertips in 10 healthy participants (6 females; age 19–24 years, mean ± SD: 20.90 ± 1.59 years) during wakefulness and non‐rapid eye movement (NREM) sleep. Our results show that during sleep, cerebral hemodynamics differ markedly from peripheral hemodynamics in both oscillation amplitude and spectral power. Furthermore, low‐frequency coupling between cerebral and peripheral hemodynamics becomes desynchronized during NREM3 sleep. These findings support the notion that NREM3 sleep plays a key role in the optimal restoration of cerebral vasomotion.