Summary
This page describes my experience with frequent arm numbness during sleep, starting in fall 2018.
I'm writing this page mostly as a record for myself, but maybe some other people will find it useful. I began writing this piece while in the process of trying to figure out my problem. Therefore, some of my early hypotheses are likely to prove wrong in retrospect, similar to how some suspects in a mystery novel later turn out to be red herrings.
Contents
The numbness
It's common for an arm or leg to "fall asleep" when you lay on it for too long. This can cause a "pins and needles" sensation, whose technical name is paresthesia. I've experienced this on random occasions throughout my life, most often when I find myself sleeping on an arm.
In fall 2018, my arms began falling asleep during sleep more and more often. When I woke up in the middle of the night, I would sometimes find that one or both arms were numb. However, often I didn't have a "pins and needles" feeling so much as just numbness—feeling as though the arm didn't have circulation, without any "pin prick" sensations. But like the ordinary "pins and needles" feeling, this numbness faded within ~5 to ~30 seconds as I began moving my arms. (I noticed the difference in feeling between this numbness and an actual "pins and needles" sensation when I had actual "pins and needles" in my right arm during the night on 2019 Jun 13.)
I sleep on my back, in the so-called "soldier" sleep position. One reason for this is that side sleeping is not really possible when you're wearing earmuffs, and I sometimes need to wear earmuffs during part of my sleep to block out noise. The soldier position also helps reduce acid reflux. And it presumably reduces the risk of sleeping on an arm in a bad way. Still, on about ~1/4 of nights, I do end up sleeping on an arm anyway due to unconscious shifting during sleep, either tilting to the side or putting my hands behind my head. Arm numbness in these cases is not unexpected.
What was weird about my numbness beginning in fall 2018 was that I often got it even if I maintained my soldier position, with my hands at my side or on my stomach. Numbness didn't happen every night, and sometimes I would go for several nights without it. But on average it did seem to happen on about ~1/2 of nights.
As far as I recall, this frequency of arm numbness had never happened before fall 2018, which seemed to rule out explanations like "it's just due to something correlated with the onset of winter weather, such as using a heavier blanket or wearing a sweatshirt".
When I'm very tired, I tend to sleep more intensely and don't wake up as much throughout the night. I noticed that my arm numbness was more likely in this case, presumably because my body was less responsive to discomfort signals. I guess this was a mild, alcohol-free form of "Saturday night palsy".
The numbness didn't hurt, nor did it wake me up. But I wanted to investigate and resolve the issue because it seemed it might be a canary in the coal mine for an underlying problem, possibly one that could cause lasting damage. Galan (2017) says: "Anyone with ongoing paresthesia should see a doctor, especially if the symptoms are new, constant, or not attributed to anything else."
The next section reviews some ideas I had about what might be causing my symptoms.
Possible causes
Arm exercise
When I read about possible causes of paresthesia, I found carpal tunnel syndrome or cubital tunnel syndrome to be some of the more plausible. Even though I have a "desk job", I doubt that my computer work would contribute too much to carpal tunnel, because I stand while working, move around a lot, take lots of breaks, and spend vastly more of my time reading rather than typing. When I do type, it's usually only a sentence or two at a time after which I pause to reread what I've written or decide what to say next, and during those pauses, I move my hands away from the keyboard (partly just to avoid accidentally hitting a key).
I thought a more likely culprit might be arm exercise with dumbbells. I began using dumbbells in 2013. (Before that I had mainly exercised just my legs, with running, walking, or stationary biking.) Because I'm lazy, I use dumbells mainly in a "cardio" way rather than for building strength: I lift the dumbells up and down for a few minutes at a time, and then set them down for a few seconds before starting again. I do this for ~30 to ~120 minutes—as long as I can go until I feel worn out.
Since ~2011, I haven't done much jogging, and cardio-style dumbbell lifting has replaced it as my most intense form of exercise. (Walking on my treadmill is my less intense supplement.) I use the same motion the whole time, bending my elbow to bring the weights closer to my chest and then back down. So it's plausible that this creates some kind of repetitive-motion stress on something.
If the culprit is dumbbell exercise, one question is why the arm numbness at night didn't really start until late 2018, more than five years after I began the habit. The weight of my dumbbells and the duration of exercise had remained roughly constant since 2014.
Dumbbell exercise is central to my physical and mental health because it's how I get my most intense cardio workout. Therefore, I haven't yet (as of mid-2019) experimented with giving it up for a long period of time in order to see if my arm numbness at night improves. Maybe I should do that at some point. What I have observed is that if I take a break from dumbbells for two to three days in a row, there doesn't seem to be much correlation with whether I'll get numbness at night. Sometimes I get strong numbness the night after long workouts. But sometimes I get strong numbness when I haven't lifted any weights for a day or two.
Posture
The other hypothesis that I thought was most plausible was that my nerves were strained by some kind of posture problem. Maybe posture while standing, but more likely posture in bed, since I only ever had arm numbness during sleep.
Of course, as with dumbbell lifting, this explanation raised the question of why the symptoms only started in fall 2018, given that my sleeping posture hadn't changed for many years.
I wanted to experiment with my mattress in case that was relevant. In Jun 2019, I dusted off a miniature mattress that I had slept on from 2011 to 2014. I laid it on top of my usual mattress. The first night I tried it, I still had arm numbness, so that experiment seemed not to be very promising. However, I tried the mini mattress again the next night, and this time I didn't use any pillow, in case that was straining my neck. This night I had no numbness. And that no-numbness trend continued for the next few nights, except on one of the nights when I turned sideways onto my left arm during sleep.
Creatine withdrawal
When I reflected on what had changed in fall 2018, one weird hypothesis came to mind: I had stopped taking creatine supplements. I had been taking a capsule containing 0.7 g of creatine almost every day from fall 2014 until fall 2018. Creatine is sometimes recommended for vegetarians like myself, although there's also speculation about possible health downsides (Tomasik "My history with creatine").
Since learning about the possible health risks of creatine, I had been thinking about discontinuing it, because it wasn't obvious that I was any better off taking it than I had been before taking it. However, because the decision was very unclear, I continued taking creatine regularly during the period 2014 to 2018, allowing me to avoid temporary withdrawal effects from going off of creatine, such as muscle achiness. Finally, in fall 2018, I happened to stop taking creatine for a few days, and I found I didn't have muscle achiness, so I decided to persist in not taking the supplement. This continued until around the beginning of 2019.
Because going off of creatine was the only physiological kind of change I could think of that coincided with the onset of my arm numbness, I decided to try taking creatine once again in Jan 2019. The night after I took my first creatine capsule, my arm numbness completely vanished. Even without taking any more capsules on subsequent days, the numbness didn't come back.
I thought it was odd that creatine withdrawal could be the culprit, because when I searched the web for {creatine paresthesia}, I found nothing relevant. On the other hand, creatine seemed to be working to banish the arm numbness. In early 2019, when I found my numbness creeping back at night, I took a creatine capsule, and the problem seemed to disappear again for a few days. That said, I didn't keep any rigorous records, and it's possible that this correlation was just in my imagination.
In Mar and Apr of 2019 I was taking a 0.7-gram creatine capsule about once every ~5 days, whenever it felt like my numbness was getting more pronounced again. It felt like the creatine also influenced my body in other ways. One night in Apr 2019 when I took a creatine capsule with a meal, I became tired and took a long nap that helped catch me up on sleep debt I had accumulated during the preceding few days. It felt subjectively like this nap was partly caused by the creatine. When I awoke from the nap, it seemed as though blood was flowing throughout my body to a degree that I hadn't felt in a while.
However, by late spring 2019, the hypothesis that creatine withdrawal was responsible for my numbness began to weaken. I stopped observing much of a correlation between taking creatine and eliminating my numbness that night. Sometimes I took creatine and still had numbness, and sometimes I didn't have numbness despite not having taken creatine in a while.
If there was any real correlation between creatine and reduction in my symptoms back in Jan 2019, my best guess would be that it was because creatine affects muscles, blood flow, etc, and probably that's somehow related to whatever the root problem is.
Earmuffs
I sometimes wear earmuffs to block out noise so that I can fall asleep. While wearing earmuffs when awake doesn't cause any symptoms, wearing them during sleep sometimes seems to restrict blood flow in my body. I can tell this because I sometimes feel blood flowing more strongly again when removing them from my head. Sometimes this restricted blood flow coincides with arm numbness that dissipates when the earmuffs are removed.
(This restriction of blood flow seems worrisome from a health perspective even without accompanying arm numbness. As of 2019 I'm still working on finding alternatives to earmuffs... Earplugs combined with background noise sometimes work, but they don't reduce sound as well as earmuffs do.)
While earmuffs seem to be an exacerbating factor, I still can have arm numbness even on nights when I don't use them, so I don't think they're the whole story, unless using them somehow caused a more permanent problem with my body.
Vitamin B12 and thyroid
In Apr 2019, I asked about my problem on the site JustAnswer. Anonymized versions of the questions and answers are published afterward, and you can see mine here: Sawhney (2019). Two of the possibilities the neurologist mentioned were as follows:
One more possible cause can be deficiency of Vitamin b12 which is essential for normal nerve functioning.
Hypothyroidism is another possible cause and can be tested for by using blood test to look at thyroid function.
I scheduled my annual physical with my primary-care physician in May 2019, and I mentioned these as two blood tests we could do, just in case they might be relevant.
I doubted that vitamin B12 would be relevant because I take a B12 supplement. And indeed, my blood test for vitamin B12 came back as 935 pg/mL, which is slightly high relative to the reference range of 213 to 816.
As for thyroid, the measurements of TSH, free T3, and free T4 all came back near the middle of their reference ranges.
Visiting doctors
I first discussed my issue with my primary-care physician, and then I was referred to an orthopedic doctor.
Both of these doctors asked me to rotate my neck and arms. Because I was able to do so without pain, that ruled out some possibilities. They also both measured my hand and arm strength by having me push, pull, grab, etc on them in various ways. I was able to pass those tests easily.
I told the orthopedic doctor that not using a pillow might have improved my situation. This, combined with the fact that my numbness was in both arms, made him suspect that it might be a neck issue. He had me do four neck X-rays, and a few minutes later, we came back to examine the results. He found that indeed I had a few things slightly off with my neck bones (although I unfortunately wasn't fast enough to write down or remember any of the technical details).
Regarding treatment, the orthopedic doctor recommended beginning with physical therapy, an anti-inflammatory prescription, heating pads, etc. No injections or surgery for now. He said posture in bed and maybe also while awake can help.
The numbness faded
Within roughly the week after visiting the orthopedic doctor, my arm numbness faded to essentially nonexistence. This wasn't because of the doctor; he had just taken X-rays and given suggestions. Rather, it seems, the improvement was due to the new miniature mattress that I was using on top of my regular mattress. This new mattress was firmer and didn't bend as much, which I assume put me in a better posture during sleep.
Between the end of June 2019 and when I'm writing this paragraph (), my former arm numbness has basically gone away. Maybe my arms have been somewhat numb during sleep roughly once a month, though I don't think they've ever been severely numb.
I should ideally still see a physical therapist some time because of the small problem in my neck, but at least that now seems less urgent.
The following paragraph is an update from . For the past year, the numbness has continued to be basically gone, even though I haven't yet done any of the things recommended by the orthopedic doctor. I think mild numbness occurred at most a few times during the last year. Even when I stop using my miniature mattress and sleep directly on my main mattress, the numbness doesn't come back. I wonder if whatever strain was causing the problem has healed somewhat? (As a comparison, in summer 2006 I slept on a couch for two weeks at the start of an internship, and for a few weeks thereafter, I had back pain. It gradually went away on its own once I started sleeping on a real bed again.)