Real-time observation of nasal cycle during sleep with polysomnography.

Purpose: To investigate the nasal cycle (NC) during sleep in healthy individuals without nasal obstruction or obstructive sleep apnoea via a flexible wearable respiratory monitoring system in a continuous and real-time manner.

Methods: NC during sleep was continuously measured in 30 healthy individuals (15 women, 15 men) via long-term sleep respiratory monitoring system, while sleep stage and body position were simultaneously recorded via polysomnography (PSG). The number of NC transitions and positional changes were documented each night. Additionally, time intervals between NC transitions and their closest positional changes during sleep were meticulously recorded to investigate potential correlations between them.

Results: A total of 86.7% of the participants displayed the classic NC, with a mean duration of 6.43 ± 2.33 h. Nightly observations revealed an average occurrence of 2.19 ± 0.40 NC transitions, predominantly occurring during REM stage (68.4%), and 9.15 ± 7.77 postural changes. Analysis of the intervals between NC transitions and positional changes revealed an average absolute value of 27.72 ± 10.85 min, with a substantial 56.4% exceeding 30 min, indicating a non-obvious sequence order among them.

Conclusion: NC can be measured in a continuous and real-time manner, the transitions occur mainly during the REM stage. However, we have not identified a clear correlation between NC transition and positional change.