The
EEG
or
electroencephalogram,
is a major part
of a sleep
study. It
measures and
records four
forms of brain
wave activity -
alpha, beta,
delta and theta
waves. Alpha
waves are
usually found
during relaxed
wakefulness,
particularly
when your eyes
are closed.
Theta waves are
seen during the
lighter sleep
stages 1 and 2,
while delta
waves occur
chiefly in deep
sleep, the
so-called "slow
wave sleep"
found in sleep
stages 3 and 4.
The EMG
or
electromyogram,
records muscle
activity such as
face twitches,
teeth grinding,
and leg
movements. It
also helps in
determining the
presence of REM
stage sleep. The
amount and
duration of
these activities
provides the
doctor important
information
about your
sleep.
The EOG
or electro-oculogram,
records eye
movements. These
movements are
important in
determining the
different sleep
stages,
particularly REM
stage sleep. The
electrodes are
usually placed
on the outer
aspect of your
right eyebrow
and along the
outer aspect
below or beneath
your left eye.
EKG or
electrocardiogram,
records heart
activities, such
as rate and
rhythm.
Electrodes are
placed on your
chest.
Nasal
Airflow Sensor:
Records breath
temperature,
airflow, apnea
and hypopnea
events. A sensor
is placed near
your nose and
mouth.
Chest/Abdomen
Belts:
Records
breathing depth,
apnea and
hypopnea events.
Elastic belts
are placed
around your
chest and
abdomen.
Oximeter:
Records blood
oxygen
saturation. A
band-aid like
clip is placed
on a finger.
Video:
Records body
positioning and
movements.
Snore
Microphone:
Records snoring.
An electrode is
placed over your
trachea, on your
lower neck.
Sleeping is a
complex activity
that must occur
for a successful
polysomnographic
study. During
sleep, our brain
and body cycle
between NREM and
REM sleep
approximately
every 90
minutes.
During these
transitions,
major changes
occur in our
EEG, EOG, EMG,
heartrate and
respiration that
are necessary
for healthy
sleep. If
abnormal changes
are observed
during a
particular sleep
stage, then we
are able to
define this
problem as it
occurs during
the night.
Some sleep
disorders are
generally worse
in a particular
sleep stage,
such as sleep
apnea during REM
sleep and PLMD
in NREM sleep.
Your PSG
technician and
sleep specialist
are well aware
of these facts
and want you to
get as good a
night's sleep as
possible in
order to make
your test
experience as
fruitful as
possible.
If you
think you or a
loved one may
have
symptoms of a
sleep disorder,
please
contact us
today.
Help
is available!
