There have been so many times recently when I have watched people fall asleep (that sounds a little creepy) and noticed that everyone twitches while they drift off.

My mom, for example, twitches really bad, especially when I try to do annoying things to here while she is sleeping (sorry, mom). My friend, who fell asleep next to me on a bus once, twitched so bad I thought he might be seizing. I know I do it too; sometimes my body jerks so hard I wake myself up. So, I decided to find out why exactly this happens.

According to bbc.com, these twitches have a name - hypnic jerks. Although no one knows for sure what causes these bodily twitches as we fall asleep, science suggests that it may be our motor system struggling to give up control of our body. The article describes how deep inside your brain, below your cortex, lies what is called reticular activating system. The reticular activating system "is nestled among the parts of the brain that govern basic physiological processes, such as breathing" and when it is in full force we are awake.

Opposing the reticular activating system is the ventrolateral preoptic nucleus (VLPO) which drives sleepiness. "As the mind gives in to its normal task of interpreting the external world, and starts to generate its own entertainment, the struggle between the reticular activating system and VLPO tilts in favour of the latter."

While we are asleep, we are normally quite still - we are in a state of sleep paralysis; but while our body struggles to give up control, our mind shoots off little bursts of energy that are displayed as hypnic jerks. Since these jerks are deemed as harmless, not much research has been done on them.

Do you jerk as you fall asleep? Have you noticed other people doing it?



Alexandra, I've certainly seen and experienced these switches before as well. In my psych class, we are learning about sleep and its stages right now. There are 4 main ones, and each is defined by differing brain waves the brain produces. In each stage, the body undergoes certain effects. I wonder if this twitching when you are in a light sleep (known as stage 1) is an impact of the theta waves, and the changing conditions of the body. In this stage, breathing becomes slow and relaxed, body temperature drops, and blood flow to the brain is reduced among other things. Maybe the body needs a little jerk as it transitions from wakefulness, where the blood is moving and the brain is alert. Movement makes blood flow faster, so maybe these jerks are a method to keep blood flowing to the brain, keep us warm, or breath more. This is just a hypothesis, but it sounds plausible to me.

If you want to look at the wave patterns, or read more about sleep stages you can check this out:

Personally, I have seen many people twitch during sleep, and I know I have woken up every now and then from a twitch. Sometimes I get confused if the twitch came from something I was dreaming or something actually happening. I know when Im at home, i see my dog laying there in a deep sleep and he is always twitching during his sleep. My mom always says that the dog is "dreaming" but after reading what you researched on the twitching in humans, makes me wonder if that would also translate into dogs as well.

It's interesting that you should blog about this, as I was just thinking about this the other day. My long-time girlfriend ALWAYS twitches as she's falling asleep, which presents a bit of an issue when we're sharing a bed-- especially when she's falling asleep before me. The first time it happened, I asked her if everything was okay, to which I got no response.

I find it interesting that scientists haven't further researched hypnotic jerks. Just because something seems harmless doesn't mean it shouldn't be observed, right?

Thanks for sharing!

I actually had quite a large problem with this about six years ago. I was working nights and supposed to be sleeping during the day. This however, was a problem for me as I had never done it before. The first two days I just ended up watching TV all day and going into work with about 2 hrs of sleep. On the third day when I went to lay down every time I got close to falling asleep I would twitch. The jolts were so much that it would push me out of sleep and I would be awake. This continued for about a month where I would twitch every time I tried to fall asleep. Eventually I was put on a sleep aid that helped me through it, but it was quite a problem that took me years to get over.

I did some research on it and actually had a sleep study done on me. When I talked to the people administering the test they told me that it was due to me being so tired that I was falling asleep too quickly. My body was reacting to me falling asleep as if I was dieing and jolting me awake to keep me from going into that state.

It was interesting to learn and scary at the same time that my body was equating me falling asleep to dieing.

Here are a few answers that I just looked up that relate to what I was talking about
what your brain thinks
yahoo answer

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