Sleep trouble, also known as sleep disorder, is a medical condition that affects the quality and quantity of sleep. Apnea is one of the most common types of sleep trouble, which is characterized by pauses in breathing during sleep. These pauses can last from a few seconds to minutes, and can occur multiple times throughout the night. People with apnea often experience excessive daytime sleepiness, fatigue, and difficulty concentrating. Treatment for apnea includes lifestyle changes, such as avoiding alcohol and sleeping on your side, as well as using a continuous positive airway pressure (CPAP) machine.