|Why do we sometimes "twitch" right before we fall
|Question Date: 2003-10-29|
That's a really great question because it's really
about our brains and consciousness. I don't think
anyone knows the answer for sure, but here's the
explanation I think is most likely.
brain is part of your body, but let's imagine your
brain and the rest of your body as two different
things for a minute. Your body sends signals to
your brain about what is happening. Your brain
sends signals to your body about what to do.
Think about some of those underwater rovers that
people use to explore places they can't go like
the Titanic. The person on the research ship gets
pictures from the cameras on the rover, then sends
signals telling the rover where to go.
Let's say they control the rover with a
cool virtual reality system where they have a
helmet showing the images from the rover and they
wear special gloves that turn their hand movements
into movements of the rover. Now let's say the
person wants to stop for lunch. The person has to
take off the helmet and gloves. Otherwise they
couldn't see their sandwich and when they reached
for it, the rover might smash its arm into the
side of the Titanic.
When you go to sleep,
especially when you dream, your brain is "taking a
break" and has to turn off most of the incoming
signals. It also has to "take off the gloves" so
that the body doesn't respond to what the sleeping
brain tells it to do. So when you're dreaming,
the images you see come from your brain instead of
your eyes. When you think about running in your
dreams, your body stays on the bed. The
controller (your brain) has cut off the connection
to the rover (your body). (It doesn't cut off
completely. A loud noise, a cat jumping on your
bed, or a sudden light can all get through and
wake you up. You also twitch and turn during your
Normally this happens quickly,
but during the change from connected to
disconnected, we sometimes feel like we're falling
and our muscles twitch. Anyway, that's my
Do you think time passes in our
dreams at the same rate that it passes in the real
world? How would you test that?
There are several reasons people might "twitch"
while trying to fall asleep. The most common kind
of twitch is called a "hypnic jerk". They happen
on occassion, especially if a person is over-tired
or sleep deprived. Some researchers think it has
to do with the muscles and nervous system reacting
suddenly during the transition phase your body
goes through while shifting from being awake to
sleep. I had a difficult time finding very much
research on the topic, probably because it doesn't
seem to be linked with any kind of illness or
medical condition. There are, however, more
serious sleep disorders that also cause twitching.
The symptoms are more serious, either in terms of
the frequency of the twitching (for example if it
happens every night for weeks on end) or in the
severity of the twitching (for example if the
twitching lasts for many seconds or minutes).
These conditions may indicate a person is having
night seizures or other problems. One of these
conditions is called "myoclonic jerks" or is also
called "periodic limb movement".
You can do
more research on this topic on the web. It is
important to be certain you are reading
information from a reliable source. I would
recommend looking at WebMD (www.webmd.com); a
medical information website with a very good
reputation for valid information, or the American
Academy of Sleep Medicine (www.aasmnet.org), a
professional organization that focuses on sleep
Sleep is very poorly understood, so I don't know
if there's a good answer to your question. Our
nervous systems do many different and mysterious
things when we're asleep, and the transition from
awake to asleep is even more mysterious, I think.
Additionally, different people's nervous systems
do different things as they fall asleep, and the
environment you're in and your emotional state as
you fall asleep all add additional
For example, many people
experience what's called hypnagogic imagery as
they fall asleep. This is kind of like
hallucinating. Some people see weird things,
others hear voices or sounds, and others feel
sensations of falling.
Twitching or movement
can be a reaction to any of those things. People
who are stressed or uncomfortable are probably
more likely to twitch or move around, but there
are exceptions to that rule, too. Some people's
twitches are very small, involving small areas in
the skin or face instead of the movement of whole
limbs. I think most neurologists would tell you
that the nervous system is too complicated for us
to know why this happens. People who study the
nervous system in sleep usually focus on brain
activity, sleep disorders, or dreams. Sometimes
information about twitching may come out of
experiments on these other aspects of sleep, but
it's not what the scientists usually focus
Great question! It would be interesting
to survey one's friends and see how different they
are in how they move as they fall asleep. Let us
know if you conduct such a survey!
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