It's impossible for me to concentrate or pay attention to anything in class! what could this be?

Attention Deficit Hyperactivity Disorder is sometimes not diagnosed until adulthood. The difficulty concentrating, focusing, problems with multitasking are often the more prominent symptoms in adulthood as opposed to hyperactivity. Neuropsychiatrists , Neurologists, Psychiatrists all see adult patients with ADD or ADHD. Careful, as an example, a disorder like sleep apnea can look like ADD.