Preliminary research suggests that CFS may involve a brain disorder -- spec=
ifically,
HPA dysfunction (see question 2.16) -- which affects the stress response sy=
stem in our
bodies. CFS patients are standardly observed to be hypersensitive to stress=
=2E Stress
does not merely mean unpleasant experiences, but rather any biological stre=
ssors,
physical or emotional, which prompt a protective reaction in the body and w=
hich may
alter the physiologic equilibrium known as "homeostasis". Stress in this ph=
ysiological
sense may be subtle and may not necessarily be noticed. Merely hearing loud=
 sounds
or seeing bright lights may be stressful in this context.

High-stress events sometimes seem to "trigger" the first appearance of the =
illness (see
question 2.06), and they will usually worsen the symptoms if the illness ha=
s already
developed. Because stress is often mistakenly thought of as a purely emotio=
nal
phenomenon with no physical aspect, the correlation of CFS with stress make=
s some
people imagine that CFS must a non-physical "psychological illness". Medica=
l studies
show that stress plays an important role in several immune-mediated illness=
es, and in
fact a new field of research called psychoneuroimmunology has been created =
to study
just this phenomenon.

HPA and neurotransmitter dysfunction may make CFS patients excessively irri=
table,
and may prompt panic attacks. These behaviors might be misinterpreted, ther=
eby
reinforcing a misconception that CFS is merely a psychological condition.

See also question 2.11 which discusses depression, and the questions under =
Part 3 of
this document, "Life problems created by CFS".