No evidence has been found that obstructive sleep apnea (OSA) increased in severity (or prevalence) as a result of vitamin D deficiency.

"Although our study was not designed to figure out why obese people have lower vitamin D levels, our results ultimately suggest that low vitamin D levels do not cause or worsen OSA," said Kunisaki. "Therefore, taking additional vitamin D supplements is not likely to prevent or improve OSA."
The researchers also found no evidence to support a link between vitamin D deficiency and increased risk of OSA in non-obese study participants.
The researchers noted that the cohort of 2,827 participants whose data were analyzed in this study were generally healthy, mostly Caucasian (92.2%), elderly males (average age 76.4 years), therefore limiting the generalizability of the study results to other populations.
Source-Eurekalert