The repeated awakenings make it hard to get a good night's sleep, resulting in poor sleep quality and sleep deprivation. The upper airway obstruction leads to decreased oxygen supply to the brain, heart and other organs and puts tremendous stress on the heart and body, leading to medical consequences in the long run.
Someone with OSA may present with loud and habitual snoring, excessive daytime sleepiness, feeling unrefreshed despite adequate sleep hours, falling asleep while driving, depression, irritation, decreased libido and morning headaches. Their sleep partners may also notice gasping and choking episodes during sleep. As the lack of sleep is very stressful, affected individuals may become irritable, undergo changes in personality, or have difficulty with memory.

Untreated OSA may lead to high blood pressure. There are also higher incidences of ischaemic heart disease, irregular heart rhythm and strokes in individuals with OSA. When OSA is severe, heart failure may occur. Untreated OSA is also associated with increased risk of sudden death and premature death.