Having MSN on while you are online is no good.
Especially when you have friends in different timezones.
One goes offline, another comes on.
You don't get any studying done.
All I remember of the 4 hours I've tried to study is the particularly disgusting fact that your respiratory duct has cells that 'sweep' mucus up from your throat - vis bacteria, the slime they produce and other assorted eeky stuff - into your oesphagus.
So basically you're constantly swallowing the various mucky stuff you breathe in.
Yucks. Horrible thought isn't it.