Table 4. Vitamin D levels and sleep apnea severity by seasons

	Summer (n=28)	Spring, fall, and winter (n=81)	p-value
Age (month)	119.9±45.7	103.7±39.5	0.08
BMI z-score	1.4±1.1	1.1±1.1	0.25
25(OH)D	23.1±8.5	18.2±6.1	<0.01*
AHI	4.8±14.5	5.6±16.3	0.81
AHI supine	5.5±14.6	6.8±18.1	0.73
ODI	9.2±15.9	9.0±17.8	0.95

Data are represented as the mean±standard deviation. p-values are from the Mann-Whitney U test for quantitative variables.
p<0.05.
BMI: body mass index, 25(OH)D: 25-hydroxyvitamin D, AHI: apnea-hypopnea index, AHI supine: apnea-hypopnea index in supine position, ODI: oxygen desaturation index.