The
real hazard of psychological
stress lies in its
manifestation with
the diver. As stress
rises, the diver
may experience anxiety,
become distracted
and suffer impaired
function. He may
suffer decreased
awareness, called
perceptual narrowing,
which causes him
to overlook things
that would normally
be obvious. This
can set up the very
thing the diver
fears; for example,
the third diver
in the previous
example, experiencing
perceptual narrowing,
fails to notice
a worn fin strap.
After entering the
water, the strap
breaks and he loses
the fin as he struggles
to reach the swim
line; without the
fin, he misses the
line and gets carried
away by the current.
With his fear realized,
his likely psychological
response is to trigger
more fears, raising
his anxiety still
farther, probably
to the panic point
unless something
or someone intervenes.
Psychological stress
also sets off physiological
responses in the
diver's body, which
may be physical
stressors themselves.
The diver may experience
nausea, vomiting,
diarrhea or a need
to urinate. The
person may become
tense and have muscular
tremors or
a headache. Adrenaline
may accelerate the
heart, or cause
an irregular heart
beat and chest pains.
Breathing accelerates,
too. If the diver's
underwater, the
breathing rate can
exceed what the
regulator can deliver,
creating a sensation
and suffocation.
At the surface,
the diver may hyperventilate
and have trouble
getting air through
his snorkel or in
splashing waves.
This makes anxiety
rise further, triggering
even more breathing
and a greater sensation
that the diver can't
get enough air.
