In fact children who grow up in clean environments are more prone to allergies and so forth. Chirldren who grew up with cows and barns rarely have any allergies and immune system problems at all. The immune system obviously needs some amount of exercise.
I also think the skin needs a break from all the shower geels.

James, I saw a fascinating BBC scientific documentary about the body clock that warned against exercise in the morning due to a negative effect on blood pressure (morning workouts can make blood pressure worse, while afternoon aerobics lower blood pressure).  Also, they claimed that the studies show that the body is under the most stress in the mornings (7am – noon), most heart attacks happen before noon on the way to work, and that those are the hours to take it easy if possible.  Next, they noted that there’s a statistical peak in road accidents at 2 PM due to post-lunch fatigue, so if all possible one should avoid driving at that time or at the very least drink a strong coffee 20 minutes beforehand.

Other notes from the show include:

– 10am – Noon = The best time for thinking and concentration
– Shortly after lunch, there is a dip in brain activity and many enter into a micro-sleep mode
– 25% of crashes are due to micro-sleeps.  (As I mentioned earlier, 2 PM has the most crashes versus 6 PM).
– Eat according to the body clock (eat more breakfast and lunch, and less dinner)
– Light affects one’s body clock, so early risers and late risers can change their habits by getting more light or less just via sunglasses usage.
– Shirt night work is not good for the body
– Testosterone is higher in the mornings, skin sensitivity and female orgasm is highest in the early evenings and late afternoons

Overall, understanding body rhythms can increase and optimize the fun stuff in life.

Last but not least, an exercise physiology book that I skimmed through had a useful study – if you do weights and cardio, it matters in which order you do them!  I forget which goes first, but the study showed that one has a relaxing effect on the blood vessels while the other had a negative effects on the blood vessels.  IMHO, it would suck to work out so hard just to cumulatively damage the body.