@article{ref1,
title="Low vitamin D levels in adults with longer time to fall asleep: US NHANES, 2005-2006",
journal="International journal of cardiology",
year="2013",
author="Shiue, Ivy",
volume="168",
number="5",
pages="5074-5075",
abstract="<p>[Abstract unavailable]</p><p>Language: en</p>",
language="en",
issn="0167-5273",
doi="10.1016/j.ijcard.2013.07.195",
url="http://dx.doi.org/10.1016/j.ijcard.2013.07.195"
}