Excessive daytime sleepiness is otherwise known as hypersomnia. There are a variety of primary sleep conditions that can cause this symptom. These include such conditions as narcolepsy, idiopathic hypersomnia, obstructive sleep apnea, periodic limb movements of sleep, and behaviorally induced insufficient sleep.
Shift Work Sleep Disorder is a real sleep disorder that may be suffered by people who work night or rotating shift. Shift Work Sleep Disorder sufferers have been shown to have higher rates of accidents, lapse of memory, impaired judgment, irritability and depression.
Insomnia is the inability to get the amount of sleep that you need to wake up feeling rested and refreshed. Commonly, insomnia symptoms include difficulty falling asleep or staying asleep during the night, sleep that feels light or restless, the need to take medications in order to sleep and sleepiness and a low energy level through the day.