There is mounting evidence for an association between sleep disorders and hypertension. In obstructive sleep apnea (OSA), there are plausible biological reasons for the development of hypertension, and treatment of OSA results in modest (2-3 mm Hg), adherence-dependent decreases in blood pressure, with larger effects evident in those with resistant hypertension. However, prospective, population-based cohort studies have not yet convincingly demonstrated a link between OSA and incident hypertension, and adequately powered controlled trials of CPAP for the prevention or treatment or hypertension are lacking. While associations have been identified between short sleep duration, insomnia, restless legs syndrome (RLS), shift work, and hypertension, the causative role of these conditions/circumstances is not proven, and further well-designed pathophysiological and/or interventional studies are needed. Particular emphasis should be placed on defining subgroups of hypertensive OSA patients that stand to benefit most from OSA treatment and in understanding the link between sleep apnea and hypertensive disorders of pregnancy. Well-controlled intervention studies are needed in populations with short sleep duration, insomnia, shift work sleep disorder, and RLS to confirm their putative links with hypertension.