head lag

can you guys please tell me more about this desease called head lag? I'm doing a research about it. I couldn't find any information about it in my library at school. I just need you guys to indicate me the right place to research it.
thank you!

[ggreg]

Well, the term you're referring to is more likely "jet lag," which is a fatigue effect that happens to people after an airline trip.  There is also a neurological thing about a lag of one-tenth of a second between the time a person sees an object and then when the brain recognizes it, and this can cause visual illusions when looking at criss-crossed line drawings.  Also, in Alzheimer's disease, sometimes their level of forgetfulness is determined according to the lag time between when they perceive an event and then forget it.  In pediatrics, when a baby is lifted and the neck muscles are not strong enough yet, the baby's head will lag or kind of lean back or to the side instead of being held upright.  I found all this by doing a regular internet search.  But jet lag is the first thing that popped in my mind, but it's not a disease, as your post said.  I think you probably should talk to your teacher about what the heck was the subject of your paper, so you don't turn in something incorrect.  Hope you find out what "head lag" is, though, if that's really the correct term, and I think we would all like to know the final outcome of your dilemma, so post back when you get it straight.