Can't speak for others.  When I have a bad cold, the quality of my work
WILL suffer.  And I'll spread any URI to my patients, which won't be
appreciated either.
    It probably depends upon the nature of work.  You don't want to overtax
yourself physically during a febrile illness.

Steve

If you have a cold and treat it properly, it will last up to fourteen days.
However, if left untreated, it will last only up to two weeks.

If someone with a cold feels up to doing something, there is no reason he
shouldn't do it. I don't think you should force yourself to doing anything,
though.

If he has influenza, I would feel very surprised if he feels up to getting
out bed to do anything other than to pee and poop. Influenza is a nasty
disease.

If you dad has influenza or noravirus gastroenteritits (the vomiting and
diarreha disease that is famous for being part of cruises, but affects far
more people in land-based outbreaks), he won't be able to do much. You don't
work yourself out of these illnesses. Likewise, if he has pneumonia or some
other illnesses, he should take it easy, going by his doctor's guidelines.

I don't think he will work himself out of being sick, but most of the time,
there is no reason to stay in bed. If he feels well enough to work, there is
no harm in working.

Jeff

Per Backspace, Backspace, Backspace:

Dunno about staying in bed, but I'd avoid strenuous activity.   The three
sickest episodes in my life correlated with having a cold or the flu and
maintaining my usual workout schedule.   In one case I wound up losing 30 pounds
and doing permanent damage to my respiratory tract - such that I cannot exercise
in air under 40 degrees F without developing a strong cough.    

My theory is that hard exercise circulates the bugs throughout my body more than
just taking it easy and that at least some of the energy going to maintaining
that level of activity is energy that could have been going to support my immune
response.

Now, when know I'm coming down with something, I cease physical activity
completely.   When I'm not sure, I'll begin activity and if I feel worse I'll
stop immediately.

My personal opinion is that those kind of statements come from people lucky
enough to have strong constitutions,  better-than-average immune systems, and/or
superior hygienic/health practices (as in not touching one's face....).  

I don't think the notion of allowing or not allowing oneself to become sick is
even remotely grounded in reality.    

If you can get more sleep, it will be beneficial, not if you're just
watching TV. The immune system works better when you're asleep.