Respiratory pauses highlight sleep architecture in mice.

Brain activity and breathing rate influence each other but it remains unclear how fine respiratory features vary across and within brain states, and how they coordinate with the micro-architecture of sleep and its associated network dynamics. Using simultaneous nasal pressure and hippocampal local field potential recordings in freely-moving mice, we show here that Wake, Rapid Eye Movement (REM) sleep, and non-REM sleep (NREM) exhibit unique respiratory signatures with distinct prominence of post-inhalation pauses. Within NREM, the emergence of pauses aligns with the infra-slow noradrenaline fluctuations and demarcate not only NREM packets traditionally defined by microarousal movements, but also shorter (~30 seconds) packets of elevated hippocampal sigma-band power. Within packets, respiratory feature changes predict moment-to-moment fluctuations in the sigma-band peak-power, even in hypoxic conditions where these infra-slow oscillations are accelerated. Overall, our findings reveal that respiratory features capture the macro- and micro-architecture of sleep, opening new windows into brain states and network computations through respiration.