I was wondering what I personally can do (habits, diets, activities) to strengthen my immune system? Thank you!

Lately, I've come to realize that I have a very powerful tendency to fall asleep in class. It seems that I can't stay awake in any lecture style class where I have to listen to the professor and take down notes — where there is minimal engagement on my part. I've pretty much fallen asleep in all of my lecture classes, during one part or another for the whole semester. I think I'm getting regular sleep — six hours at a minimum. I don't like to drink coffee or anything.

1) I read the information on your website about knuckle cracking, and I was wondering if it applies to cracking backs and necks. I know that people often have their backs cracked by friends, etc. because it feels good and seems to relieve tension. Also, when my neck feels tight, I often turn it from side to side until it cracks and feels better. I've heard that chiropractors do some version of this, and call it "realignment." Is this safe? Is there a right or a wrong way to crack a back or neck? Is cracking your back/neck actually therapeutic in some way?

2) As a college student, I sometimes spend long hours reading books or looking at computer screens, and often my neck gets stiff. Like many of my joints that get stiff, sometimes I crack my neck, like I would crack my knees or fingers when they feel stiff. I often wind up doing this several times a day.

My question is, could I do irreparable damage to my spinal system if I continue using this method to soothe a stiff neck? Could I wind up a paraplegic if I continue to crack my neck? Leak spinal fluid, etc.?

When is a person with a cold contagious? A couple of friends, who are put off when I keep my distance from their sneezing and coughing, insist one is only contagious a week or so before symptoms appear. In the back of my memory is the idea that one remains contagious until a few days *after* primary symptoms disappear. I'm not usually so concerned about this, but I'm coping with a couple of other annoying health problems and want to try to avoid adding a cold or flu, to boot. I do the usual things news shows recommend — eat well, wash hands frequently. But when should one avoid others who have colds, or when should one stay isolated at home when one has a cold (or flu)?

Is sleeping on our left side in any way harmful for the heart (or anything else)? Some people tell me we shouldn't do it and others tell me it's actually better than sleeping on our right side. What's the truth?

Thanks!

What do you know about the medical uses of acupuncture and acupressure? Have either of these practices been helpful in treating any medical conditions? Thank you for any information you can provide me.