Sleep phases

stenberg at cc.helsinki.fi stenberg at cc.helsinki.fi
Fri Feb 14 11:40:47 EST 1992

In article <27269 at skye.dcs.ed.ac.uk>, jt at dcs.ed.ac.uk (Sebastian Theriault) writes:
> Hello all,
> is there an easy way to detect in what phase of sleep a person
> is in (deep sleep, REM etc...). The detection mechanism must not
> require human intervention. 
> I want to build an alarm clock that wakes me up when I'm not in a deep
> sleep (at a time closest to what I set the alarm to).
You need to monitor the EEG using two electrodes glued to the skin of the
scalp (those held in place by rubber bands might get dislocated). The
electrodes are connected to the inputs of an amplifier, which amplifies the
100-400 microvolt signals to 1-4 volts. You can use this signal to trigger
the alarm (in "deep sleep" there are high-amplitude slow waves, "delta"
waves) or preferably first band-pass filter the 0.5 - 4 cps band before
using the signal for detecting the delta. I can see no way of detecting
deep (delta) sleep without an EEG.
Oh... you do not by any chance mean REM sleep by "deep" sleep?? This would
not be correct, as the treshold for awakening is lower during REM sleep
than during delta wave sleep. On the other hand, muscle tone is even lower
during REM sleep than during deep sleep, although there are occasional
muscle twitches. The interest in REM sleep naturally comes from the fact
that most dreaming takes place during this state. If you want 
to detect REM sleep instead of deep sleep you are not greatly helped by the
EEG, as there is no specific sign of REM sleep there. Using the same type
of electrode on both sides of an eye (or diagonally around an eye) will
monitor eye movements, and provided you are not awake these should indicate
REM sleep. It is a bit tricky to ensure that the detector detects only the
REM type of eye movement. There are commercial devices for this purpose.
(the deep sleep, delta wave detector should be possible to adapt from
commercial alpha or theta feedback devices).

Dag Stenberg                            stenberg at cc.helsinki.fi
Department of Physiology                stenberg at finuh.bitnet
University of Helsinki                  tlx: 1002125 finuh sf
Siltavuorenpenger 20 J                  fax: int.+358-0-1918681
SF-00170 Helsinki, Finland              tel: int.+358-0-1918532

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