What is the medical end in of 'dazing off'?

the other day someone be talking to me while i be eating and i literally didn't hear anything they be said -- it was close to i had dazed past its sell-by date into space for a second and when my mind clicked back contained by they had to repeat themselves - what is the medical source for 'dazing off' what causes this? does it come to pass to everyone?What is the medical end in of 'dazing off'?
There can be any number of causes for a conditional lapse of attention, like from a want of proper sleep (you are tired & so is your brain), or stress (your brain is engaged within thinking about something else, possibly something that worries you, it is VERY difficult to uphold attention/focus when you are worried or thinking about something else). If it happen alot, it can be from a temporary insufficiency of blood supply to the area of the brain which maintain attention, as in ADD/ADHD, or it could be a short time ago plain boredom. It is common, especially within this hectic, distracting world, but there are ways to revise to stay focused. Hope this helps.
There can be lots causes for this my daughter is 8, she used to do this commonly , we thought she was a short time ago ignoring us close to a typical kid buried in T.V. and she be also doing this at school , on Dec. 18th she have a seizure. We took her to a neurologist to find out that she be actually have constant seizures within the lower left lobe of her brain, she is immediately on medication for this. If it continues i would definitely return with it checked out.