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published 1/28/08, updated 10/30/09

Insomnia Until it Hurts

The role of sleep deprivation in muscle pain

by Paul Ingraham, Vancouver, Canada MORE

Credentials and qualifications

I am a writer and retired Registered Massage Therapist (unusually well-trained for a massage therapist, a 3000-hour program). I’m almost done with a Bachelor of Health Sciences degree. I am a peer reviewer for The Natural Standard, and a copyeditor for Science-Based Medicine. My most important qualification is more than a decade of workaholic post-graduate study, clinical experience, and constant conversations with readers from around the world, including many experts who have provided countless suggestions and criticisms.

For more information, see: Who Am I to Say? More information about my qualifications, credentials and professional experiences for my readers and customers.


We are used to thinking of insomnia as a symptom of stress — and it is.12 However, it is also hazardous itself. Based on personal experience and clinical observation, I have long believed that the pain and stiffness of myofascial trigger points — muscle knots — is probably aggravated by insomnia or even mild but chronic sleep deprivation. There is no direct scientific evidence to support this (to the best of my knowledge), but there is plenty of indirect evidence. In this article I’ll discuss what little is known, and what we might reasonably guess, about the relationship between sleep disturbance and muscle pain.

The broad biological importance of sleep

Certainly serious insomnia is nothing to mess around with. Insomnia is not generally fatal, of course, because there are all kinds of self-preservation mechanisms that kick in. But unchecked sleep deprivation can actually kill. Laboratory animals subjected to extreme sleep deprivation die relatively swiftly of unknown causes — exactly what goes wrong is not clear, but their body temperatures start to drop and then they suffer rapid and widespread physiological failure. So sleep is actually required for life — for all life, in fact. Virtually every living organism sleeps, if it has any kind of a brain of any kind at all.

This strongly suggests that sleep-deprivation is potentially dangerous stuff, even when it isn’t lethal. A poison at a non-fatal dosage is still poisonous.3 And in fact there is a considerable amount of science confirming this general hypothesis. In his 1996 book, Sleep Thieves: An eye-opening exploration into the science and mysteries of sleep, Dr. Stanely Coren describes sleep deprivation studies in humans showing a number of ominous effects, and he generally makes a strong case that everyone needs to take sleep deprivation much more seriously than we generally do. Here are some other examples from more recent scientific research:

So sleep deprivation involves some ominous potential hazards. But what about pain?

Does insomnia cause pain generally?

Before trying to figure out if insomnia makes trigger points worse, a logical question to ask is: does it make any kind of pain worse? Yes, it probably does. “According to the majority of the studies, sleep deprivation produces hyperalgesic changes.”9 Here’s a fairly persuasive selection of the many available research examples:

In 2007, Smith et al experimentally messed with the sleep of 32 innocent women, and found that they were significantly more pain-sensitive, although in that case the effect was caused by sleep discontinuity, not deprivation alone (most insomniacs face both problems).10

An internet survey of over 2,500 people with fibromyalgia (a chronic pain condition) showed that insomnia was one of the most commonly identified aggravating factors.11 Whatever fibromyalgics find uncomfortable may be moving healthier people in the direction of increased sensitivity as well — they are a canary in the neurological mine. Simply put, if sleep deprivation does hurt, then fibromyalgics will notice it more readily than other people, and this is at least consistent with the fact that fibromyalgics believe that sleeplessness aggravates their symptoms.

Another survey found the fairly spectacular statistic that 53% of chronic low back pain patients had insomnia, compared with only 3% in pain-free controls.12 Critical thinkers will immediately suggest that it’s most likely that low back pain that is keeping these people awake, but I don’t think that’s obvious at all. The jury must remain out for me. My clinical experience suggests that it’s just the opposite: chronic low back pain patients are often poor sleepers, and insomnia may routinely precede episodes of pain! All of this is also discussed in advanced low back pain tutorial.

And fortunately I’m not alone in this fairly counterintuitive idea. Kundermann et al write, “Although it is well documented that subjects with different pain syndromes suffer from sleep disturbances, the direction of cause and effect in this relationship is still a matter of debate.”13

Do things hurt more? Or does it just seem that way?

This is a very thorny question, almost a philosophical question. It is well agreed in pain science that “seeming” is the whole ball of wax, the only thing that matters: if something seems painful, it is. But we can still observe that some seemingly painful things are associated with measurable changes in tissues, while other seemingly painful experiences seem to occur in the absence of any such changes, and this difference is obviously of interest, and we’d like to identify it if we can. For instance, we mostly know about trigger points because they hurt, but only relatively recently in medical history have we begun to identify the tissue changes associated with that pain!

The lack of such signs in the tissues does not indicate an imaginary or hysterical pain, but either that we simply can’t identify an associated change in the tissues, or the difference exists in the complex functioning of the central nervous system itself — not so much a pain that’s “all in the your head” in the psychological sense, but a pain that’s “all in your brain and spinal cord.”

And all pain is also mediated by psychology. There is no such thing as pain that is “all in your body” — it’s impossible. See Pain Is an Opinion for more about that interesting idea.

In 2004, Kundermann et al tried specifically to approach this question of whether or not pain associated with sleep deprivation involves an “organic” change in the tissues, or is simply a differince how painful things seem. They tested whether or not sleep deprivation changed perception in general or only pain perception. The result was definitely the latter. Pain sensitivity was increased without any other general effects on physical sensations, strongly suggesting that something “actually” hurt more, as opposed to just “seeming” that way (“without alteration of somatosensation in general”).

The authors concluded, “Because this suggests an effect truly specific for pain, research may now focus on its underlying mechanisms of action.”14

Such as …

The case for insomnia as an aggravator of trigger points

Insomnia doesn’t just cause pain in general, and it doesn’t do it just by mucking with the volume of all your nerves. It also almost certainly causes musculoskeletal pain specifically. We’ve already given the examples of the effects on fibromyalgia patients and migraine sufferers. But insomnia is also a cause of increased muscle pain in normal, healthy people. This is getting awfully close to trigger points …

Moldofsky et al’s sleep deprived subjects “reported more musculoskeletal symptoms” and “a significant increase in muscle tenderness.”15 The same researchers repeated those results in a second study.16 In 1999 Lenssinck et al found in their sleep-deprived subjects a whopping “24% decrease in musculoskeletal pain threshold.”17 That’s tenderness in the muscles specifically — sensitivity to poking or “mechanical” stimualtion — as opposed to sensitivity to cold or heat as is the case in many of the studies mentioned previously.

Another sleep-deprivation study of nine men in 2001 showed that pain sensitivity increased 8% with a “sleep debt” of 40 hours (40 hours of lost sleep with no opportunity to recover). Even more interesting, letting them catch up actually had a much greater pain-relieving effect — “greater than the analgesia induced by level I analgesic compounds.” Cool!18

And so on.

We are still a long way from “proving” that insomnia affects trigger points specifically or directly. None of these studies even begin to try to correlate pain sensitivity and musculoskeletal symptoms with trigger points specifically. And how could they? A lot of the scientific know-how needed to reliably measure the presence and severity of trigger points is barely any older than this sleep research, and only a few people on Earth have it.

But there is plenty of reason here to make an educated guess that a lot of that increased sensitivity is related to trigger point formation. If we pull back from the science for a moment and think about our subjective experience, if we know that most pain and stiffness is caused by trigger points, then we also know that sleep loss makes them worse: who hasn’t had the experience of having a bad night and feeling distinctly stiffer, achier, more sensitive to pressure? Who hasn’t noticed that it is precisely such a morning when you are most likely to suffer from at least a tension headache, if not a migraine as shown in one of the studies mentioned earlier? Who hasn’t wished especially hard for a good shoulder squeeze after sleeping badly?

These common experiences are definitely consistent with trigger point aggravation. It is likely that there is a whole mess of physiology and psychology that produces those effects, numerous factors above and beyond trigger points alone. But it is also quite reasonable to imagine that the effect is dominated by a straightforward worsening of the same pain and stiffness caused by trigger points that we feel even when we’ve slept perfectly well. And this would be a good use of Occam’s razor (Wikipedia) — let’s not make this too much more complicated than it has to be!

A personal perspective

I am a massage therapist largely because I am an unusually “triggery” person — I am one of those people who just seems to have more than his fair share of trigger point discomfort. I relate well to my patients. I have been highly motivated to learn study the phenomenon of muscle pain.

In 2005, when I suffered from a particularly long and severe bout of insomnia, sleeping less than 4 hours per night for many weeks at a time, I experienced an inexorable increase in pain of all kinds, but especially trigger point pain. Every familiar old knot became loud and then vicious, and without question these sensations became the single most debilitating consequence of my insomnia.

Like Carl Sagan famously suggested, I try not to “think with my gut” and patiently wait for science to clarify the situation, one study at a time — it is okay to be uncertainmeanwhile. But if there is a topic in musculoskeletal health care that I have a “hunch” about, it’s this: insomnia is probably food for trigger points!


Notes

  1. Knutson et al. Archives of Internal Medicine. 2009. Reduced sleep duration and quality are associated with elevated blood pressure, according to researchers with the CARDIA study. They used wrist activity monitors to monitor associations between sleep behaviors and BP among more than 500 adults in their 30s and 40s, finding that shorter sleep duration and poorer sleep maintenance were each associated with increased systolic and diastolic BP. The authors say the sleep-BP link is supported by previous research and “laboratory evidence of increased sympathetic nervous activity as a likely mechanism underlying the increase in BP after sleep loss.” <#comments#> Return to text.
  2. U.S. Department of Health and Human Services. Morbidity & Mortality Weekly Report. 2009. People unemployed or unable to work were at increased risk of sleep loss — likely due to the stress. And sleep insufficiency is most prevalent among those aged 25 to 34 and least among those 65 and older, which I think is also probably related to stress: people tend to suffer a lot more stress earlier in their careers. Return to text.
  3. Actually, many astute readers will know that this is crap: most medicines are toxic in high dosages, and many so-called “poisons” are actually used as medicines in low dosages. But this is a case of “you know what I mean” — a lot of sleep deprivation is a bad thing, and a smaller amount of sleep deprivation is still a bad thing, just less of it. Return to text.
  4. Alstadhaug et al. Headache. 2007. This study of 1869 incidents of migraine clearly showed that “sleep obviously protects against [migraine] attacks rather than provokes them,” while a whopping 29% were actually caused by insomnia. I don’t know about you, but anything that protects against migraine attacks is good and I don’t want to lose much of it. Return to text.
  5. Akerstedt et al. Journal of Sleep Research. 2007. From the abstract: “… disturbed sleep and fatigue are predictors of long-term absence [from work due to sickness] and it is suggested that impaired sleep may be part of a chain of causation, considering its effects on fatigue.” Return to text.
  6. Ohayon et al. Journal of Psychiatric Research. 2003. Return to text.
  7. Neckelmann et al. Sleep. 2007. The results of this very large and well-conducted survey are “consistent with insomnia being a risk factor for the development of anxiety disorders.” Return to text.
  8. Roth et al. Clin Cornerstone. 2003. Return to text.
  9. Kundermann et al. Pain Res Manag. 2004. Return to text.
  10. Smith et al. Sleep. 2007. Return to text.
  11. Bennett et al. BMC Musculoskeletal Disorders. 2007. Return to text.
  12. Tang et al. Journal of Sleep Research. 2007. Return to text.
  13. Kundermann et al. Psychosom Med. 2004. Return to text.
  14. Kundermann et al. Psychosom Med. 2004. Return to text.
  15. Moldofsky et al. Psychosom Med. 1976. Return to text.
  16. Moldofsky et al. Psychosom Med. 1975. Return to text.
  17. Lenssinck et al. Pain. 2004. Return to text.
  18. Onen et al. Journal of Sleep Research. 2001. Return to text.