Vitamin D deficiency (VDD) may be associated with obstructive sleep apnea (OSA) presence and is more pronounced with increasing OSA severity; however, the relationship between these two entities remains unclear. This was a cross-sectional study among 262 adults with in-hospital-attended polysomnography-diagnosed OSA and no additional major comorbidities, aiming to explore possible associations between serum 25-hydroxyvitamin D [25(OH)D] levels and polysomnographic parameters. Data on demographics, medical history, anthropometric indices, and lifestyle habits were collected at enrolment. Serum 25(OH)D was evaluated using chemiluminescence, with VDD defined as 25(OH)D p 2 [3.38 (1.52–7.52)], but not in the younger and non-obese adults. This study provides further evidence of an inverse association between vitamin D levels and OSA severity and underscores the importance of considering vitamin D status as a potential modifiable factor in the comprehensive management of OSA.
