The Mystery of My Periodic Limb Movement Disorder

I have restless legs syndrome (RLS) and have had it for years. I was not aware at all of another disorder commonly occurring with RLS that can be quite disruptive to my partner in bed with me. I’m not aware of it because it is a twitching of my limbs while I am completely asleep.

What is periodic limb movement disorder?

About 80 percent of people with RLS also have what is called periodic limb movement disorder (PLMD). It is often characterized by rhythmic limb movements between 20 to 40 seconds apart involving one or both limbs.^1,2

With me, it appears to be a rhythmic sort of kicking every 20 seconds or so. In fact, it is not unusual for me to kick myself awake on a regular basis with a sudden jerk or spasm. I often find that even when napping, I will suddenly kick or jerk my leg, suddenly jolting me awake.

I had always assumed these were hypnic jerks — except they are excessive for me and not at all rare, and at times they are quite violent, while hypnic jerks are generally benign.³

They also did not occur while just falling asleep as I thought a hypnic jerk would. Sometimes I was deep asleep when they woke me up. I had no idea that it was something I was doing all night long.

I was unaware I was moving during sleep

My spouse is a heavy sleeper. In that sense, it is near impossible to wake him, even if I do kick him — which, apparently, I might. I was only ever aware of PLMD in its most violent occurrences of jerks or spasms of my limbs that woke me from my own deep sleep.

I experienced this in both my arms and legs, but usually just in my legs.  I wasn’t aware I was moving at all during sleep. I was only aware of being woken up with these violent spasms once in a while. Certainly, I couldn’t figure out what that was about.

Going off of clonazepam clued me in

I would never have known what it was because a treatment often used is clonazepam, and I was on that for some time as a vestibular suppressant. I can only assume this was suppressed at that time even though the RLS was not.

It was not too long ago I went off of that and my spouse became aware, awakened by my nocturnal kicking. As I said, he is a deep, deep sleeper. Only recently he has been alert at night and unable to get back to sleep because of my constant movements.

The mystery ghost in my bed

I speculate it is occurring while I am relaxed and trying to fall asleep. This is called periodic limb movements during wakefulness (PLMA).⁴

However, if it is, I am not entirely aware of it. What I am aware of is the sensation of the bed moving at the base, and that I can’t seem to explain. It is moving. That I know for a fact. I just do not feel like I am the cause of that movement.

The movement I feel is sort of rhythmic, so that makes me suspicious in many ways that I am, in fact, the cause of this movement and entirely unaware of it. How strange is that? I sure would like to know if PLMA is the cause of that strangeness.

I'm also extremely sensitive to motion due to a vestibular condition, so even the slightest movement seems exaggerated to my brain. If it isn't this, well, then it's Casper the Friendly Ghost and he's really annoying! Or my spouse has the same exact thing and I feel his and he mine when we try to sleep!

That theory may very well turn out to be true, as he has disturbed sleep patterns but not restless legs syndrome. This could be primary PLMD. To solve this mystery, one or both of us would need a sleep study.

Confirming PLMD (someday)

When my spouse described it to me, I knew exactly what it was, having read about it. It was just a matter of describing it to my neurologist, then. The likely culprit is periodic limb movement disorder (PLMD). A sleep study would confirm this, but being in a pandemic, that will have to wait for some time.

Treatment in the meantime

However, when I take my levodopa for restless legs syndrome, it seems to resolve both problems at the same time. My spouse has not noticed it happening now, and I have not woken up with the more violent presentations of it, either.

Frankly, my restless legs syndrome is so aggressive I tend to take the levodopa in the evening and again at night, so as a result, it helps with the PLMD occurrences for me. I am glad this mystery is figured out, because I have poor sleep and insomnia. I really do not need any nocturnal movements disrupting me more.

Do you experience periodic limb movement disorder? How did you discover that you have it? Tell us more in the comments below!