Festive medical myths

I was rather disappointed with the section "You can cure a
hangover . ." in “Seasonal Medical Myths . .” in the BMJ
Christmas issue, vol. 337, p.1443. Known physiology can
surely provide some basis for treatment, and there have
been articles in the BMJ suggesting that massive blind
crossed-over trials are not always essential, particularly
where that is the case.

In the note quoted water is
mentioned once, in the first sentence, coupled with
Vegemite (whatever that is). It has been known at least
since the days of Shakespeare that excessive consumption of
alcohol causes loss of body water [reference surely not
necessary: it is to the Porter in Macbeth; I haven't got
an edition of Shakespeare that gives line numbers]. From
1942 onwards I was working in the late Professor R. A.
McCance's Department of Experimental Medicine for the Royal
Navy on the problems of survival at sea. These of course
include lack of drinkable water. Prof. McCance was a great
practiser and teacher of 'do-it-on-yourself' physiology.

In the course of the work I noticed that the symptoms of
experimental dehydration corresponded closely with those of
a hangover. A few years later I found myself in uniform as
the doctor on a small flat-bottomed minesweeper (HMS
Truelove: as it happened I was engaged at the time) on
Fisheries Protection duty but also to test the new Naval
life-raft (the ancestor of all current life-rafts) in Artic
waters in early spring. The evening before we were to sail
at 0600 into the North Sea from Rosyth, the wardroom
officers (about six in number) came to me and demanded
preventative treatment for any hangovers. With difficulty,
I managed to persuade them that only drinking water would
work. "Right, Doc, we'll take you at your word", they
responded -- I thought a little threateningly. At about
midnight they returned to the wardroom, carrying trays
laden with pint glasses of water, which they proceeded to
down. I heard no more from them -- which I regard as
positive evidence -- and the ship sailed on time into a
rough sea with all hands in good shape.

I do in all
seriousness recommend an adequate dose of water as an
effective (and cost-effective) treatment. (I am not in any
way disparaging proper comparative trials where possible
and appropriate. When we compared motion sickness
preventative drugs in the early 1950s, the design of the
double-blind crossed-over trials, which I was responsible
for, was quoted as an early example of good design.)

G. R. Hervey, Emeritus Professor, University of Leeds, and
sometime Chairman, Survival at Sea Sub-Committee, Royal
Naval Personnel Committee.

Competing interests:
None declared

I agree that the simple statement that "40-50% of body heat" is lost
through
the head is inaccurate. The true statement is that at – 4 degC half the
heat
production of a resting (clad) man may be lost through the head and that
at –
15 degC this may rise to 70%. Also in normal circumstances people do not
venture into the cold wearing only swimsuits. The head is also different
to
other parts of the body.

1. The insulating layer of subcutaneous fat over the head is much
less than
over the rest of the body, and becomes even less in the elderly.

2. Vasoconstriction is much less effective over the head.

3. The head has a covering of hair over a large area which provides
some
additional protection but, mainly in males, this covering becomes less
with
age though the extent varies.

4. Covering the head reduces heat loss caused by temperature
difference
between the skin and the environment. However the effect of wind and wet
are much more important (factors often not measured in laboratory studies)

and using a hat provides protection from these factors as well.

5. In babies, where the surface area of the head is a much larger
proportion
of the total body surface than in adults, and the brain is a major heat-
producing organ, prevention of heat loss from the head can be critical.
In
fact the use of a close fitting gamgee-lined hat reduced the rate of fall
of
core temperature in a naked neonate, and also reduced the oxygen
consumption. The same gamgee insulation over the lower abdomen did not
have a measureable effect.

6. During personal experience of camping above the snow line with
an
inferior sleeping bag, I found that I felt too cold and uncomfortable to
sleep
till I put on a wooly hat. I then slept comfortably.

To summarise, covering the head in cold weather can produce a marked
effect in subjective comfort and reduction of heat loss. I would hate
to think that this myth-busting exercise, while discouraging them from
venturing out in swimwear, may lead to people going out in very
cold weather (cold, windy and wet) without bothering to protect their
heads.

References
All these points, except number 6, are cited in
Lloyd Evan L Hypothermia and Cold Stress. Croom Helm, Kent. 1986.

Competing interests:
None declared