Static stretches are part of an effective cool down because they can a) revert lactic acid b) improve performance c) decrease blood flow d) increase endurance

Hi, 
The answer to this question is C. :)
Hope this helps!

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