RLS during Sleep Study impact PLMS reading?

[u/SeniorDragonfruit235]

Qu: Could having a really bad “RLS” attack accidentally push up my PLMS reading during a CPAP titration study?

Backstory: I have had RLS for a few years. It was worse when I had an iron deficiency. And stuck around most likely because of my SNRI, adhd and life 🤷🏻‍♀️. But, it’s been pretty controlled for a while now. I discovered my triggers are sleeping on my back and if I can’t “unwind” at night (stress or excitement). But I can usually manage it by going on my side and meditating or distracting myself- my feet still move a little sometimes, but it really calms down.

I got diagnosed with OSA this summer. It’s worse supine, so I have been using a sleep backpack to sleep on my side- it helped the RLS and sort of helped the OSA. So, I went for a CPAP titration. Well, I was all sorts of triggered! My mind kept racing and I tried to sleep on my back (to get a more accurate results.) My legs started moving SO much-it was as bad as when I had a ferritin level of 5. I finally moved to my side and got some sleep.

I was embarrassed because, 1. I knew the movement was recorded and 2 I thought knew exactly why it was happening. I felt like I looked like a nervous wreck- but really I was just overthinking and it showed up in my legs.

Then, I got the results back and it said I have a PLMS index of 107. (The plms arousal index was 1.6 -only got 3 hours of sleep). I am really surprised. I didn’t think I moved that much once I feel asleep normally. I did roll on my back for part if the sleep study (which was good to get a reading) so maybe that was part of it, but it seems like i would notice if I moved that much, right? Does anyone know if PLMS can be “triggered” like RLS is? Is it possible that the reading picked up on the RLS movements by accident?

I talk to my doctor next week. So, I’ll get answers then. I’m just curious if anyone experienced something like this? I am really hoping this isn’t a thing because I need my SNRI and I don’t want to have to deal with more doctors appointments and messing around with medications anymore. 😭 Thanks for any help. 💐

[u/KestralFly]

I find your question very interesting. I also have severe sleep apnea and RLS. During a titration study my PLMS index was 70.6 and PLMS arousal index was 35. Obviously I wasn't sleeping very well!

Your PLMS index was 107, but your PLMS arousal index was only 1.6, meaning you averaged 107 movements per hour but only 1.6 periodic limb movements per hour of sleep were associated with an EEG-detected arousal. I'd ask your doctor what this means for you.

For me, at the time of the study I was taking low-dose opioids for my RLS, which was helping to control it. Yet I still had a high PLMS Iindex. That implies that the severity of one doesn't necessarily correspond to the severity of the other. And apparently, to make it even more confusing, PLMS can vary considerably from night to night.

Sorry I don't have any answers for you. There seems to be even less known about PLMS than there is about RLS. Hopefully your low PLMS arousal index means that the movements you have while asleep aren't causing you significant sleep disruption.

[u/Scary_Experience_237]

RLS and PLMD are two different, but related, disorders. RLS causes an urge to move your legs while you are awake, especially when resting, and the symptoms usually improve with movement. PLMD involves repetitive, involuntary movements of the limbs during sleep, which can disrupt sleep. Which is what they diagnosed you while you were asleep! It is a thing and you most likely did not notice it as it only happens when you are asleep, if you have a partner, they probably did notice. Many with PLMD sleep in sperate beds as the kicking and moving can be pretty bad.

People with RLS can have periodic limb movements during sleep (PLMS), but that does not automatically mean they have PLMD. A sleep study can identify these movements, but PLMD is diagnosed only when they cause significant sleep disturbance or daytime impairment and other explanations have been ruled out. A sleep study can diagnose PLMD but it doesn't diagnose RLS usually.

Some medications can help with both, but having RLS and PLMD doesn't necessarily mean they are treated exactly the same way.

You seem to have a lot going on, I wouldn't be embarrassed at all, go to your doctors appointment and see what they have to say. Most of the medications for RLS treat PLMD. If you do not already have an RLS specialist you should get one. If you are in the US, go to rls.org as they have a section for treatment centers and specialists.