Does our swallow go to sleep? Changes in swallow function during sleep and implications for symptoms.

Abstract

Swallowing is a vital function and the clearance of the pharynx by deglutition, which removes matter that could be aspirated, and the respiratory phase patterns associated with deglutition are important in protecting the airways and lungs against aspiration. This article reviews swallowing and respiratory phase patterns associated with deglutition during sleep and their implications for pathophysiology. During sleep, swallowing is infrequent and absent for long periods. The deeper the sleep stage, the lower the mean deglutition frequency. However, in healthy younger adults, sleep-related deglutition is almost always followed by arrested breathing and expiration, reducing the risk of aspiration. Deglutition is extremely infrequent as well as absent for long periods in the aged. Consequently, clearance of the pharynx and esophagus by deglutition was extremely reduced during sleep in the aged. Furthermore, respiratory phase patterns associated with deglutition displayed adverse patterns during sleep in the aged. Due to the complexity of swallowing processes, many adverse health conditions can influence swallowing functions during sleep, especially in the aged. Sleep-related deglutition and respiratory phase patterns may adversely influence aspiration-related diseases such as aspiration pneumonia, especially in the aged not only with primary but also with secondary presbyphagia.