causes of needing to sleep a lot
But nodding off when you want or need to be awake may also be caused by an underlying condition. Depression or a sleep disorder -- such as restless legs syndrome, sleep apnea, or narcolepsy -- are common causes of problem sleepiness.
Sleep Apnea and Excessive Sleepiness. Sleep apnea is becoming a more common cause of sleepiness in children and adults. Sleep apnea occurs when the upper airway collapses for at least 10 seconds during sleep -- and does so up to hundreds of times each night. Obstructive sleep apnea is the result of a blockage in the airway.