Table 1.

Demographics, sleep and respiratory characteristics of the subjects

Variables	Control (n=8)	OSA (n=18)
Age (years)	41 ± 11	50 ± 17
Gender (male/female)	1/7	6/12
BMI (kg/m2)	32.4 ± 5.1	37.5 ± 12.1
Sleep efficiency (%)	81.5 ± 11.8	74.8 ± 14.9
Sleep stage changes	16.5 (13.0 – 21.0)	27.1 (19.7 – 38.7) §
Sleep architecture
-NREM1 (%)	7.7 (4.6 – 11.1)	15.2 (8.8 – 19.9)
-NREM2 (%)	61.1 (53.0 – 63.2)	62.3 (45.9 – 74.8)
-NREM3 (%)	10.1 (8.8 – 16.6)	6.2 (0 – 13.3)
-REM (%)	17.9 (13.1 – 22.2)	11.2 (3.3 – 15.1) *
Arousal index (events /hour)	10.1 (8.6 – 13.7)	18.8 (12.0 – 29.9) *
AHI (events/hour)	0.9 (0.7 – 1.6)	21.5 (10.7 – 39.3) ***
ODI (events/hour)	0.9 (0.7 – 1.4)	22.6 (9.8 – 38.3) ***
Average SpO2 (%)	96 ± 1	94 ± 3

Continuous variables with normal distribution are expressed as mean ± SD and compared with ANOVA. Continuous variables with skewed distribution are expressed as median (interquartile range) and compared with Mann Whitney U test. Categorical variable was expressed as fractions and compared with Chi-squared test. The duration of each sleep stage is expressed as percentage of total sleep time.

^*p<0.05

^***p<0.001

^§p=0.066 vs control group.

AHI, apnea/hypopnea index; BMI, body mass index; NREM1, NREM2 and NREM3, non-REM sleep stage 1, stage 2 and stage 3; ODI, oxygen desaturation index; OSA, obstructive sleep apnea; REM, rapid eye movement sleep; SpO2, pulse oxygen saturation.