Abstract: Objective The present study aims to explore the relationship between olfactory dysfunction and sleep structure parameters in patients diagnosed with obstructive sleep apnoea hypopnoea syndrome(OSAHS). In addition, the study will seek to identify the predictive factors affecting olfactory function, with a view to providing a new perspective on the study of multi-system damage in OSAHS. Methods A cross-sectional study design was adopted to retrospectively analyze the data of 198 patients diagnosed with obstructive sleep apnea-hypopnea syndrome(OSAHS)through polysomnography(PSG)from December 1, 2020 to June 30, 2024. The Sniffin' Sticks olfactory test kit was used to assess olfactory function, and PSG was employed to record sleep structure parameters, including total sleep time(TST), sleep efficiency(SE), percentage of N3 sleep(N3%), percentage of rapid eye movement sleep(REM%), apnea-hypopnea index(AHI), and lowest oxygen saturation(LSaO₂). Pearson and Spearman correlation analyses were used to explore the correlation between sleep structure parameters and olfactory function. Multivariate logistic regression was applied to analyze the independent influence of each sleep parameter on olfactory impairment. Results The proportion of males and age demographics in the olfactory disorder group of OSAHS patients were higher than those in the normal olfactory group(P<0.05). The total sleep time(TST), sleep efficiency(SE), total number of microarousals in the rapid eye movement(REM)sleep period and non-rapid eye movement(NREM)sleep period, N3/TST%, and REM/TST% in the olfactory disorder group were lower than those in the normal olfactory group(P<0.05). The apnea-hypopnea index(AHI)and wake time after sleep onset(WASO)in the olfactory disorder group were longer than those in the normal olfactory group(P<0.05). The olfactory threshold(Threshold, T), discrimination ability(Discrimination, D), identification ability(Identification, I), and the total score of olfactory threshold + discrimination In the study, the mean scores for ability and identification ability(TDI)in the olfactory disorder group were found to be lower than those in the normal olfactory group(P<0.05). A relevant analysis demonstrates a negative correlation between the total score of TDI and age, as well as AHI and WASO. In contrast, a positive correlation is observed between TDI and TST, SE, the total number of micro-awakenings in the REM stage, and REM/TST%. The findings of the logistic regression analysis indicated that age, AHI and REM/TST% were independent factors that influenced TDI. Conclusion Increased age, elevated apnea-hypopnea index(AHI), and decreased proportion of rapid eye movement(REM)sleep(REM/TST%)have been identified as independent influencing factors for olfactory disorders. The decline in olfactory function has been found to be significantly associated with a marked reduction in REM sleep. Patients suffering from obstructive sleep apnoea-hypopnoea syndrome(OSAHS)who are elderly, have a high apnoeahypopnoea index(AHI), and a low proportion of rapid eye movement(REM)sleep should be the key population for olfactory function screening.

Key words: Obstructive sleep apnea, Olfactory function, Sleep structure, analysis of Influencing factors