Is vitamin d deficiency linked to bad sleep?

Vitamin D deficiency: If you shun the sun, suffer from milk allergies, or have a strict vegan diet, you may have vitamin D deficiency. In older adults it may lead to cognitive impairment, but am unaware that it produces sleep disturbances. Serotonin, the brain hormone associated with mood elevation, rises with exposure to bright light and falls with decreased sun exposure and this has been associated with depression.

It can be: linked to problems with sleep.

Possibly: In our brain, there are vitamin D receptors that control our biological clocks, biorhythms & master clock too affecting all organs in the body.So there's implication that different neurotransmitters are also Vitamin D3 dependent, including melatonin. Insomnia can have over 20 different reasons why it occurs, not just a single vitamin/hormone deficiency. Ask your Doctor for her/his recommendations.