The condition can be difficult to pinpoint, especially for those who sleep and/or live alone, in which case their sleep is wholly unobserved. Some individuals report a dry mouth on awakening, as well as the daytime fatigue that is a hallmark of the condition and is sometimes the only observable indication that a person has sleep apnea. Waking frequently during the night and being a restless sleeper are additional, though less common, symptoms that people may be able to observe in themselves.