II. Causes: Sleep deprivation
- Most common cause of excessive Daytime Sleepiness
- Sleep deprivation adversely affects neurobehavioral functioning after 1 night and is cummulative
III. Causes: Neurologic
- Narcolepsy (Prevalence: Up to 0.18% of general population)
- Idiopathic daytime Hypersomnolence (accounts for 10% of suspected Narcolepsy cases)
- Neurologic Injury or disorder
- Myoclonic Movements
IV. Causes: Psychiatric and Lifestyle Habits
- Major Depression
- Poor Sleep Hygiene
- Circadian Rhythm abnormalities (nightshift changes, Jet Lag)
V. Causes: Comorbid medical illness
- Sleep Apnea (most common)
- Congestive Heart Failure
- Chronic Obstructive Pulmonary Disease
- Coronary Artery Disease
- Anemia
- Hypothyroidism
- Mononucleosis or other viral syndrome