Why do some people gag when someone is vomiting?

Why is it that when a person vomits, it causes others to vomit — even when they don't have an illness causing it? Is this something triggered by the brain or is it something that happens by reflex (survival instinct) for someone to vomit since, perhaps, what the first person was eating may affect the second who vomits as well?


Is neck and back cracking all it's cracked up to be?

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.?


Why do I get flushed and tired after eating lunch?

I find that when I eat lunch I can feel myself instantly get tired as if a wave passes through me. My face gets a feeling of being sweaty and flushed. Coffee and copious amounts of water help counteract this. Also, it doesn't happen every day with every meal. Very small amounts of food don't cause this. It's as if I eat above a small threshold, then it happens. It makes it hard to work. A short nap would be perfect (but not possible). Is this something to be worried about?


What are the effects of calorie counting and intermittent fasting?

1) I've started counting calories in order to lose weight, and I've lost ten pounds in six months, so I'm positive that counting calories works. Recently I've started to eat one big meal (about 1400 calories) a day. Is this healthy? Will I continue to lose weight?

2) During the day, I keep a strict paleo diet and end eating at 10PM and Begin eating at 12 PM the next day. Around 10:30 AM the next day, I do full a body weight training session and begin eating at 12 PM. Basically, I only drink water during my fast or keep calories to a five calorie maximum. After the fast, I eat whatever I want (paleo that is). I'm trying to get my body to use excess fat as energy, therefore causing me to lose body fat and gain muscle faster. I feel great and I have witnessed fast results, (increased strength and leanness) within a month and half of intermittent fasting. My question is do you think intermittent fasting is unsafe? Or just a new an effective way to see increased health?


Do cosmetics containing sunscreen provide adequate sun protection?

I was thinking of buying a face powder that says it has an spf of 30. It seems convenient to have a powder sunblock since lotions make my oily face greasy. However, I was wondering if this powder will even be effective as a sunblock since I heard that some moisturizers and other products that advertise an added SPF sometimes don't have a high enough concentration of sunblocking ingredients to make it effective. I would like to know what do you think before I make my purchase.


When are colds contagious?

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)?