Carbon dioxide loss sustains instability

This proposed hypothesis asks whether hot flashes can leave sleep unstable after the flashes are suppressed. A randomized awakening may cause overbreathing that lowers carbon dioxide. The drop may slow breathing, then trigger bursts that reactivate the autonomic system, which controls heart rate and blood pressure. A lab study would give each participant sham gas delivery and isocapnic control, which keeps carbon dioxide steady, during verified hot-flash suppression. Shorter recovery and faster return to sleep with control would support the proposed loop; persistent instability would weaken it. Testing needs controlled gas delivery, carbon-dioxide monitoring and sleep recording.