• excessive daytime sleepiness
• frequent episodes of obstructed breathing during sleep. 
  (The patient may be unaware of this symptom -- usually the bed partner is extremely aware of this).

Associated features may include:

• loud snoring
• morning headaches
• unrefreshing sleep
• a dry mouth upon awakening
• chest retraction during sleep in young children (chest pulls in)
• high blood pressure
• overweight
• irritability
• change in personality
• depression
• difficulty concentrating
• excessive perspiring during sleep
• heartburn
• reduced libido
• insomnia
• frequent nocturnal urination (nocturia)
• restless sleep
• nocturnal snorting, gasping, choking (may wake self up)
• rapid weight gain
• confusion upon awakening