Which of the following represents a scanner creates a magnetic field around you, then pulses radio waves at the tissues being studied; and is often used to identify tumors or other types of brain damage? a) EEG
b) fMRI
c) PET
d) MRI

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