Sleep-disordered breathing (SDB) is common and adversely affects cardiovascular
morbidity and mortality. Despite multifactorial pathogenesis, SDB is prevalent in patients with fluid
retention disorders, such as drug-resistant hypertension, end-stage renal disease, and heart failure,
suggesting that fluid retention may play a role in the pathogenesis of SDB. During the day, fluid is
likely to accumulate in the legs, and upon lying down at night is displaced from the legs. Many data
suggest that some of this fluid displaced from the legs may redistribute to the upper body and
predispose to SDB. This review article will highlight evidence for a relationship between SDB and
fluid retention or rostral fluid shift, and discuss mechanisms that link them.