Describe how urine is formed, beginning with the blood.

Filtration, reabsorption, and secretion are all mechanisms that the nephrons of the kidneys use to absorb blood and produce urine. Urine is made of 95 percent water and 5% human waste. Urea, creatinine, ammonia, and uric acid are nitrogenous wastes excreted in urine.
Explanation:

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