Why Do People 'Twitch' When Falling Asleep?

[Still Waters]

A hypnagogic jerk is an involuntary muscle spasm that occurs as a person is drifting off to sleep.

Some scientists believe certain factors, such as stress, anxiety, fatigue, caffeine and sleep deprivation, may increase the frequency or severity of hypnagogic jerks, but conclusive research is lacking on the subject.

Researchers are also unsure why hypnic jerks occur, but a few theories exist.

http://www.livescien...^editors_choice

[Himawari69]

I'm no scientist so I don't know why, but it's kinda funny when you see someone jerk in there sleep. Sometimes I feel my arms or legs jerk when I'm drifting to sleep, I don't think it's sleep deprivation or caffeine tho as I don't drink coffe nor do I have problems sleeping.

[Skep B]

Himawari, sounds like muscle spasms as your body is getting ready for rest

As for jerks, i lean towards the explanation already suggested

[stevemagegod]

my theory is that its the bodies way of testing us if we are truly are a sleep before Sleep Paralysis kicks in to keep us from acting out dreams.

Edited September 1, 2013 by stevemagegod

[sarah_444]

I get the falling sensation occasionally but it's always accompanied by a dream where I'm falling. I never know if I feel like I'm falling because of the dream, or I dream that up because of the sensation I'm feeling.

Something I started thinking about while reading this was the startle reflex a lot of newborns have. They suddenly throw their arms back and get this terrified look of their faces as if the feel like they are falling. It happens while they are sleeping and usually wakes them up, (until they learn to sleep through them) but I know it can happen when they are awake as well. Makes me wonder if it's related to hypnagogic jerks at all.

[brlesq1]

All I know is that it wakes me up and then I can't get back to sleep...grr.

[Frank Merton]

I've heard of this but never experienced it, so it is not universal and may in fact be uncommon.

[little_dreamer]

It happens to me a lot. It's like your body says "Last call for consciousness!". I bet it wakes up a lot of people who might otherwise fall asleep behind the wheel.

[Drayno]

My girlfriend actually has this problem..

When she's asleep she'll jolt around a lot.

I've always assumed it had to do with dreams.

[Frank Merton]

Kinda like cats do? I always figured they were dreaming about catching mice.

[Professor T]

I've heard of this but never experienced it, so it is not universal and may in fact be uncommon.

Wow.. Are you saying you have never, ever, experienced it?

I can experience it quite often, and the trick to doing so is to follow your self to sleep.. By that I mean laying back, staying still, and staying aware while your body starts to drift off to sleep.. The trick to is to stay still, don't move.. Also, to keep your thoughts on your body and awareness of the moment, not drifting off to past, future, or self indulgent thought streams.. More often than not, your thought's end up elsewhere then WHAM, I usually experience a partial or full body hypnagogic jerk..

[Frank Merton]

Generally I lie down and wham I'm out. I think it comes of getting up early every morning 'cause I can't sleep in daylight.

[spacecowboy342]

I saw something on the science channel yesterday about the involuntary spasm that happens sometimes when you are drifting off to sleep. They were saying it was a vestigial reaction from a time when our ancestors slept in trees and falling asleep could lead to falling out of the tree

[Frank Merton]

Chimps sleep in trees and build nests, I guess so they won't fall out. I would think an involuntary twitch would be more likely to cause a fall.

[spacecowboy342]

Chimps sleep in trees and build nests, I guess so they won't fall out. I would think an involuntary twitch would be more likely to cause a fall.

More like a startle reaction when drifting off to prevent falling. Don't know if chimps experience this or not

[Michelle]

More like a startle reaction when drifting off to prevent falling. Don't know if chimps experience this or not

As I understand it, it is a defense mechanism. It's like a lot of people can't sleep on an airplane, bus or whatever, because they don't want to fall over into the person in the next seat. When they start to drift off they will jerk awake.

[spacecowboy342]

As I understand it, it is a defense mechanism. It's like a lot of people can't sleep on an airplane, bus or whatever, because they don't want to fall over into the person in the next seat. When they start to drift off they will jerk awake.

Yeah, something like that. It's like your brain kind of panics for a second when it realizes it's losing control and startles you awake

[Drayno]

Kinda like cats do? I always figured they were dreaming about catching mice.

Some thing very similar to this, yes.

[White Crane Feather]

Falling out of trees dosnt ring true to me because other non primate animals do this, but generally when you are just starting to fall asleep you lay motionless for pretty long. My guess is that it prevents blood clots while falling asleep. Your body cannot stay motionless for to long. There have been problems with this with people under anestisa, now they have a device that massages your muscles to prevent them.

Edited September 3, 2013 by White Crane Feather

[cacoseraph]

Falling out of trees dosnt ring true to me because other non primate animals do this, but generally when you are just starting to fall asleep you lay motionless for pretty long. My guess is that it prevents blood clots while falling asleep. Your body cannot stay motionless for to long. There have been problems with this with people under anestisa, now they have a device that massages your muscles to prevent them.

What!?

That is what happens after days of being in the same position. it is not from being asleep for 8h, it is from being more or less immobile. And generally blood clots are not the first problem. Bed sores and stuff happen first. In the old days bed sores were very very bad as they lead to terminal infections. Generally blood clots are the result of an illness or other malfunction, not just being bedridden.

From what I have read hypnic jerks are something along the lines of the normal procedure of unconsciousness immediately followed by sleep paralysis getting just a wee bit messed up. I don't think any complete analysis of cause has been put out and in all likelihood there are multiple ways it can happen. As it turns out the human brain is kinda complex.

[White Crane Feather]

What!?

That is what happens after days of being in the same position. it is not from being asleep for 8h, it is from being more or less immobile. And generally blood clots are not the first problem. Bed sores and stuff happen first. In the old days bed sores were very very bad as they lead to terminal infections. Generally blood clots are the result of an illness or other malfunction, not just being bedridden.

That's what my anesthesiologist told me right before he put the contraption on my legg before a surgery. I have also looked into cases where people have died by passing out but not moveing at all for as little as 4 hours. I'm no doctor, but I am certain one told me about it.

http://drugtools.caremark.com/topic/dvt

Yup remaining motionless for extended periods creates a an environment for dangerous blood clots. When you are motionless for quite a while if you jerk and shift you weight you could effectively stop blood clots from forming. Just a guess though

Edited September 3, 2013 by White Crane Feather

[cacoseraph]

That's what my anesthesiologist told me right before he put the contraption on my legg before a surgery. I have also looked into cases where people have died by passing out but not moveing at all for as little as 4 hours. I'm no doctor, but I am certain one told me about it.

http://drugtools.car...k.com/topic/dvt

my gut says that site is rubbish, but anyhow " 56 cases of pulmonary embolisms experienced by passengers at Charles de Gaulle Airport in France between November 1993 and December 2000" do you know how many ppl flew through there in 6-7 years? Hundreds of thousands. The fact that 56 experienced... something is more more indicative of preexisting conditions that happened to manifest rather than some objectively causative agent from sitting still for 8-16h. Cuz really, what you are claiming is that humans haven't adequately adapted to sleeping. Really?! REALLY!!

Plus, the incidence of hypnic jerk is so low and spotty that it probably doesn't serve a medically therapeutic purpose.

[White Crane Feather]

my gut says that site is rubbish, but anyhow " 56 cases of pulmonary embolisms experienced by passengers at Charles de Gaulle Airport in France between November 1993 and December 2000" do you know how many ppl flew through there in 6-7 years? Hundreds of thousands. The fact that 56 experienced... something is more more indicative of preexisting conditions that happened to manifest rather than some objectively causative agent from sitting still for 8-16h. Cuz really, what you are claiming is that humans haven't adequately adapted to sleeping. Really?! REALLY!!

Plus, the incidence of hypnic jerk is so low and spotty that it probably doesn't serve a medically therapeutic purpose.

I wouldn't take that much of a jerk to dislodge tiny clots starting to form. I think you missed the point. The jerk would be the adaptation to stop clots when you are motionless for to long. Like many things the human body dosnt always get it right. We are absolutely not perfectly evolved. You would think the human body would have adequately adapted to giving birth to, but surprise surprise the simple act ( or not so simple) of procreation is excruciating and highly dangerous. Especially before modern technology. It's just not the way that evolution works. Things go wrong.

Immobility: Most commonly, when the body stops moving, the risk of blood clots increases, since muscle movement is required to pump blood towards the heart. Stagnant blood in a vein is prone to clot.

http://www.medicinenet.com/script/main/mobileart.asp?articlekey=99124&page=5

http://www.medicinenet.com/script/main/mobileart.asp?articlekey=154386

Actually it's starting to make more sense now. The jerks do seemed to be more pronounced when in awkward positions like in planes and driving. Rarely have I witnessed or have had them in bed.

Edited September 3, 2013 by White Crane Feather

[cacoseraph]

clots would presumably form from fibroblasts? Well, how can I heal my cuts and wounds when I keep walking around. Surely my day to day activity imparts more kinetic energy preventing forming into fibroblastic clots than a random (and not occuring in even remotely nearly all humans) jerk while falling asleep?

I guess if you wanted to claim hypnic jerks were necessary in some weird subset of humans I would have a harder time claiming against, but otherwise, it just freaking doesn't make sense!

[spacecowboy342]

I wouldn't take that much of a jerk to dislodge tiny clots starting to form. I think you missed the point. The jerk would be the adaptation to stop clots when you are motionless for to long. Like many things the human body dosnt always get it right. We are absolutely not perfectly evolved. You would think the human body would have adequately adapted to giving birth to, but surprise surprise the simple act ( or not so simple) of procreation is excruciating and highly dangerous. Especially before modern technology. It's just not the way that evolution works. Things go wrong.

http://www.medicinen...ey=99124&page=5

http://www.medicinen...ticlekey=154386

Actually it's starting to make more sense now. The jerks do seemed to be more pronounced when in awkward positions like in planes and driving. Rarely have I witnessed or have had them in bed.

That may be true for you but not for me. There may be some individual variance for this and there also conditions such as sleep apnea but I frequently have a startle response that jerks me awake as I drift off in my bed.