Researchers from Aarhus University Hospital, Brendstrupgaardsvej, Aarhus,
Denmark, discovered that sleep-deprived individuals urinated more frequently
with greater salt content in the urine. This was more true for males than
Circadian rhythms are believed to be the factor behind urination patterns.
Under healthy sleep conditions, frequency of urination is diminished at
nighttime to allow for uninterrupted sleep.
The researchers concluded that sleep deprivation, which creates a change in
the body’s hemodynamics (blood flow), hormonal production and other factors,
prevented the naturally occurring nocturnal lowering of blood pressure. This
explains the lower levels of nighttime plasma rennin, angiotensin II and
aldosterone (sodium production regulators), and thus an increase in sodium
and potassium excretion.
Additionally, frequency in urination from loss of sleep was attributed to
blood pressure in the kidney producing an osmotic diuresis. The mechanism
behind the patterns of urination in daytime versus nighttime is not yet
clear, nor is it understood why one sex is affected more than the other.
The findings will be presented at “Sleep Deprivation and Nocturnal Urine
Output – Gender Difference in the Effect,” at the upcoming conference, Sex
and Gender in Cardiovascular-Renal Physiology and Pathophysiology, sponsored
by the American Physiological Society.