Hypopnea is breathing that is shallower or slower than normal. Hypopnea is underbreathing. Hypopnea is different from apnea in which there is no breathing. People with hypopnea often have loud, heavy snoring. Other indicators of hypopnea are: * daytime sleepiness * depression * forgetfulness * mood or behavior changes * trouble concentrating * loss of energy * nervousness * morning headaches Consequences of hypopnea include: CPAP is the most common treatment for hypopnea.