Vitamin D insufficiency is common in the healthy population. Recent insights addressed the role of vitamin D in serotonin and melatonin regulation, suggesting that increasing vitamin D status may be helpful for improving mood and sleep. This literature review covers the current state of evidence regarding potential effects of vitamin D on mood and sleep indicators in healthy people. In total, 11 observational studies were found for sleep, and 54 studies on mood (including ten RCTs). These studies revealed mixed results for both sleep and mood. The findings were interpreted based on the previously proposed serotonergic pathway of vitamin D. Implications and challenges for future research regarding the timing of blood sampling, timing and dosage of supplement intake and investigating the response dynamics are discussed.