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EMBARGOED
FOR RELEASE UNTIL
August 8, 2007
APS Contact
Donna Krupa
Office:
(301) 634-7253
Cell: (703) 967-2751
dkrupa@the-aps.org
Acute Sleep Deprivation
Leads To Changes In Nighttime Urine
Production For Men And Women
Lack of
sleep causes men to produce more urine than women, making “bathroom breaks”
likely
Austin, TX – Our body’s production of urine
follows a circadian rhythm. During the day, we experience greater urinary
frequency; at night, urine production declines, enabling us to get
uninterrupted sleep. The regulation of urine excretion during nighttime
hours is influenced by many factors, including hormones, blood flow (hemodynamics),
and sleep-related factors. The mechanism behind the day/night changes is not
yet clear. Danish researchers have examined the urinary patterns of
sleep-deprived volunteers and have found that a lack of sleep leads to
increased urinary output and more salt in urine. The findings were found to
be more prevalent in males than females.
The Study
The study team is comprised of Birgitte Mahler,
Kostantinos Kamperis, Soeren Hagstroem, Eva Radvanska, Soren Rittig, and
J.C. Djurhuus, all of the Aarhus University Hospital, Brendstrupgaardsvej,
Aarhus, Denmark. Dr. Mahler will present her team’s findings, entitled,
“Sleep Deprivation and Nocturnal Urine Output – Gender Difference in the
Effect,” at the upcoming conference, Sex and Gender in
Cardiovascular-Renal Physiology and Pathophysiology. The meeting,
sponsored by the American Physiological Society (APS;
www.The-APS.org), is being held
August 9-12, 2007 at the Hyatt Regency Austin on Town Lake, Austin, TX.
Methodology
Twenty healthy volunteers (ten males; ten females;
19-35 years of age) underwent two 24-hour circadian in-patient studies under
standardized conditions for diet and fluid intake. Participants were sleep
deprived during one of the two sessions in a randomized sequence. Their
blood pressure and heart rate were recorded every hour using a non-invasive
blood pressure monitor. Electrolytes, osmolarity, creatine and urea were
evaluated in plasma and urine. Key blood elements were also measured.
Excretions and clearances were calculated for electrolytes and osmoles.
Key Findings
There were no significant differences in the quantity
or contents of the daytime urine examined in both experimental periods.
Following the sleep deprivation period, however, both genders produced
markedly larger amounts of urine. This effect was significantly more
pronounced in males than females.
Sleep deprivation reduced the nighttime dip in blood
pressure which can explain the lower levels of nighttime plasma rennin,
angiotensin II and aldosterone and the increase in sodium and potassium
excretion. The relatively higher blood pressure on sleep deprivation nights
may also have affected the blood pressure in the kidney producing an osmotic
diuresis.
The researchers found that during nighttime, acute
sleep deprivation leads to:
-
an increased urine output more evident in males
-
a reduced fall in blood pressure (reduced nighttime dip)
-
lower levels of sodium regulating hormones (plasma rennin,
angiotensin II and aldosterone)
-
excessive excretion of osmoles (sodium and potassium).
A change in the body’s hemodynamics, caused by sleep
deprivation, seems to account for these observations.
***
The
American Physiological Society (APS;
www.The-APS.org) has been an integral part of the scientific discovery
process since it was established in 1887. Physiology is the study of
how molecules, cells, tissues and organs function to create health or
disease.
# # #
NOTE TO EDITORS: The APS meeting is being held
August 9-12, 2007 at the Hyatt Regency Austin on Town Lake, Austin, TX.
Members of the media are invited to attend the sessions. To schedule an
interview with Dr. Mahler, please contact Donna Krupa at 301.634.7209
(direct dial), 703.967.2751 (cell) or
DKrupa@the-APS.org.
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