Hi cornellian,
According to a American Family Physician article, ?Night sweats are
a common outpatient complaint, yet literature on the subject is
scarce.? I easily concur! The exact physiology of nocturnal sweating
is not clear.
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=12643362&dopt=Citation
The short answer, from what is known, lies in the hypothalamus, the
part of the brain that regulates body temperature and some aspects of
metabolism. Triggers such as hormones, alcohol and some drugs can
trick the hypothalamus into believing the body is cooler than it
really is. To compensate, the hypothalamus responds by raising body
temperature. Since the body, in good health, was not actually cool,
this results in an elevated body temperature. In order to cool itself
down, the body begins to sweat. Of course, in pneumonia and other
infectious diseases, the body is infected with bacteria or a virus,
and may already have an elevated temperature from a fever. Bacteria
and viruses produce toxins, which are known as ?pyrogens?-fever
stimulators. Hormones and other body proteins can function as pyrogens
as well!
The pyrogens raise the body temperature, causing the body to attempt
to conserve heat. One way of conserving heat is to constrict the blood
vessels to prevent heat loss. This alone can raise the body
temperature 2-3 degrees. Raising the body temperature makes life
difficult for most bacteria and viruses, and they either die or
reproduce much slower.
So, why does a fever turn into night sweats? Circadian rhythm. Body
temperature, respiration, pulse, and metabolism are all decreased at
night. Many hormones that can fool the hypothalamus are secreted in
large amounts at night. Often, people with high fevers at night have a
near normal temperature in the morning, thanks to diurnal variations
(a variation in temperature throughout the day and night). Increased
pyrogens, a fever, diurnal variations, medications, and high levels of
secreted hormones can all contribute to night fevers, and their
consequential sweats!
?In healthy individuals, the body temperature (oral temperature) is
somewhere between 36,5 and 37,5 . It slightly increases during the
day since the morning (from 6:00 a.m.). The peak is reached at 6:00 to
10:00 p.m. The lowest temperature is between 2:00 and 4:00 a.m.
Diurnal variation depends on the activity throughout the day. Diurnal
variations don't change in persons that work at night and sleep during
the day. Such a diurnal variation is also kept when fever occurs.
Fever reaches the peak in the evening, and in the morning even a very
sick patient may have almost normal temperature. Body temperature
changes are more intensive in young person than in old people.?
http://nic.sav.sk/logos/books/scientific/node45.html
?A good example is temperature regulation. When body temperature
increases, neurons in the anterior part of the hypothalamus turn on
mechanisms for heat dissipation that include sweating and dilation of
blood vessels in the skin. When body temperature decreases, neurons in
the posterior part of the hypothalamus are responsible for heat
production through shivering, vasoconstriction in the skin, and
blockage of perspiration.?
http://www.neuroanatomy.wisc.edu/coursebook/neuro2(2).pdf
http://sleepdisorders.about.com/cs/sweats/a/sweatbasics.htm
Fever Physiology
http://www.hawaii.edu/medicine/pediatrics/pedtext/s06c03.html
I hope this has clarified things for you. If any part of my answer is
unclear, please request an Answer Clarification, before rating. I will
be happy to respond as soon as possible.
Regards,
crabcakes
Search Terms
nocturnal hydrosis
hypothalamus + fever
metabolism + thermoregulation |
