Why might folic acid be used as a supplement

If you're pregnant or might become pregnant, it's critically important to get enough folic acid, the synthetic form of vitamin B9, also known as folate.

Folic acid helps prevent neural tube defects (NTDs) – serious birth defects of the spinal cord (such as spina bifida) and the brain (such as anencephaly). The neural tube is the part of the embryo from which your baby's spine and brain develop. NTDs affect about 3,000 pregnancies a year in the United States

-When pregnant, taking a Folic Acid supplement helps lower the risk of birth defects
-A Folic Acid supplement is also sometimes used to treat Folic Acid deficiency and some kinds of anemia 

Because without physical activity, the body has extra "energy" if you will, and so when it is time for bed you are not tired, so you end up staying up all night. also there is probably an effect on your internal clock, which messes with your melatonin production which goes hand in hand with your sleep cycle