2 4.1.4 Quiz: Muscle Madness Question 3 of 5
Exercise can do which of the following?
O A. Make more fast- or slow-twitch fibers.
B. Evaporate muscle fiber.
C. Make more muscle fiber.
D. Reduce the amount of muscle fiber

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

Smoking damages the respiratory system by inhalation of a foreign substance, that is absorbed and residue is left behind on our lungs sponge like substance. the gas that is inhaled also increase your blood pressure and dilates your blood vessels. also the process of inhaling and exhaling the smoke it causes irritation to the throat and mouth. smoking can cause lung cancer and other respiratory and circulatory diseases.