Abstract
The purpose of this study is to investigate the relationship between the human nasal cycle and circadian rhythm. Both sides of nasal breathing were measured with small thermistors and the time-series data were converted into digital data. The nasal cycle was obtained by calculating the switching duration of a predominant side of nasal breathing. The experimental results showed that the frequency of the nasal cycle is high in the daytime compared with that in the early morning and at night, suggesting that the nasal cycle was influenced by circadian rhythm.
