Chronic dehydration is associated with obstructive sleep apnoea syndrome

We were interested to read the recent review article in Clinical Science concerning OSA (obstructive sleep apnoea) and its connections to obesity, diabetes and hypertension [1]. That article looked into the evidence supporting the association of OSA with hypertension, and described the different associated health problems of obesity, hypoxia and cardiovascular disease and the difficulty in finding successful treatments, even using animal models. Similar points have been laid out recently in an editorial published in the New England Journal of Medicine [2]. However, one important aspect that appears to have been overlooked in the review [1] and in the editorial [2], is, with sleep apnoea, the mouth is open sometimes for considerable periods of time. With chronic open mouth breathing there is considerable loss of water leading to chronic dehydration. Appropriate physiological responses to intracellular dehydration (increased osmolality) are thirst (drinking) and...