One in three Americans is missing this key vitamin, and it explains why you can’t sleep

One in every three Americans may not be getting enough of a vitamin essential for controlling sleep, according to a new health warning. The vitamin in question is vitamin D, often referred to as the ‘sunshine vitamin,’ and medical experts believe that a shortage may be the cause of common sleep problems, particularly as winter approaches.

When skin is exposed to ultraviolet (UV) radiation from sunshine, the body naturally produces vitamin D. However, such levels frequently decline during the winter or in areas with limited sunshine.

Low vitamin D levels can disrupt the body's circadian rhythm, or internal clock, according to Dr Otulana, a general practitioner in the UK's national health system. More than one-third of Americans don't get enough vitamin D, which is affecting their sleep, t