Sensible advice for aches, pains & injuries

Morning Back Pain

A thorough review of possible causes for this frustrating symptom

updated (first published 2007)
by Paul Ingraham, Vancouver, Canadabio
I am a science writer and a former Registered Massage Therapist with a decade of experience treating tough pain cases. I was the Assistant Editor of for several years. I’ve written hundreds of articles and several books, and I’m known for readable but heavily referenced analysis, with a touch of sass. I am a runner and ultimate player. • more about memore about

“I woke up with it” is an amazingly common description of how low back pain started. (And neck pain and headaches. And even more.1). Is sleeping dangerous? Probably not: waking up with back pain rarely indicates a serious problem.

Many people get their first acute episode of low back pain during the night, and the AM effect is also a dreaded part of chronic low back pain. Even many people who are more or less pain-free during the day — people who would never think of themselves as victims of chronic pain — nevertheless experience routine and significant irritation and stiffness first thing in the morning.

Maybe there are opportunities for treatment in changing the way we sleep.

Photograph of an unmade bed, representing the relationship between sleep and back pain.

Is pain and stiffness your alarm clock? Do you bail out of bed early every morning with low back pain, neck pain, and more?

What causes flare ups of back pain in the morning?

Lita Scruton of Ontario asked me for an explanation of her morning back pain:

Every morning I awaken stiff and have to get out of bed. No sleeping past 7am for me, ever! I can’t take the discomfort. So why during the day I can do anything, even exercise, and have no discomfort? Why do my muscles get so painful while I am suppose to be relaxed and resting? If I awaken during the night to use the bathroom they feel great, but any time after 6am, it is a whole different story. Can you help me solve this mystery?

There are three main explanations for morning back pain:

  1. Inflammatory back pain: worrisome, relatively rare, and fairly well known.
  2. Myofascial pain syndrome and/or fibromyalgia: probably extremely common, but more mysterious and controversial.
  3. Sleeping postures: although the most “obvious” reason for waking up with a kink in your back, it might be worse than you expect.

Inflammatory back pain is the scary one

The closest thing to back pain that truly “likes” the morning is inflammatory back pain (IBP), or spondyloarthritis.2 Although IBP is well known to medical science, its biology is mostly mysterious, and morning symptoms specifically are a stumper, just as unexplained as joints that ache before a storm. It’s just something IBP does.

But don’t panic! Although studies have confirmed that morning is a common time for inflammatory back pain to flare up, they have also shown that the connection is not strong or exclusive.3 In fact, most morning stiffness and pain is not inflammatory. It’s just that IBP is the only official morning back pain culprit.

The pain of IBP tends to be quite severe. If it’s not actually waking you up, it’s probably not IBP, or it’s a minor case.

But nastier and unusually consistent morning symptoms are good cause to consider the possibility of IBP. The diagnosis is also more likely if you have other signs of this kind of back pain. Here’s a good inflammatory back pain quiz, and here’s my own a quick checklist of reasons to ask your doctor about spondyloarthritis:4

Technically IBP causes night back pain, not morning back pain

The morning pain of IBP is actually a case of leftover nighttime symptoms, which wear off as you wake up and get moving. When the symptoms are milder, you will mostly sleep through them, noticing them only when you wake up. But these symptoms will usually be obvious while you are still in bed, as soon as you are conscious — or even waking you up early.

In contrast, pain that you don’t notice until you actually get up and start trying to move around is less likely to be inflammatory in nature. But these are rules of thumb only, of course — there’s always lots of exceptions in biology.

Myofascial pain syndrome and/or fibromyalgia

There are two common causes for widespread moderate body pain, both somewhat mysterious and controversial, both affecting the back more than other areas, and both known for their morning hijinks:

  1. Myofascial pain syndrome (MPS) is an infestation of too many “trigger points” — sore, aching patches of soft tissue that often seem to ease with massage and heat, but which are mostly unexplained and difficult to treat.
  2. Fibromyalgia (FM), a disease of increased sensitivity generally and decreased pain threshold, fatigue and sleep disturbance, and the “fibro fog” (mental confusion).

There’s likely lots of overlap between these conditions. While FM is more clearly a neurological disease, and MPS is hypothetically a problem with muscle tissue, they seem to cause many of the same symptoms, and each condition probably aggravates the other.

Fibromyalgia is associated with morning back pain because:

  1. People with FM rarely feel rested, because the condition either causes or is caused by fragmented sleep and a lack of deep restorative sleep. The fatigue makes any pain worse, and this is probably felt mostly acutely in the morning, gradually (and imperfectly) yielding to the stimulations of the day: exercise, sunlight, coffee, people, noise and so on. The morning-ness of fibromyalgia pain could also just be “one of those things,” an unexplained rhythm of the disease.
  2. Although FM causes widespread pain by definition, back pain is particularly common.

And trigger points may be strongly associated with morning back pain because:

  1. Tissue stagnancy and postural strain seem to be a major cause of flare ups of trigger point pain, and both are an issue at night: we are often pretzeled into awkward positions in our sleep, and often for long periods.
  2. The paraspinal muscles seem to be particularly vulnerable to trigger points.

Notice that both FM and MPS seem to affect the back particularly. It may be that they each affect the back in their own special nasty way… or it could be two sides of the same coin. Perhaps fibromyalgia affects the back more than other areas because it causes vulnerability to trigger point… which occur in the back muscles much more than other muscles.5

Fibromyalgia and MPS both probably exist on a wide spectrum of severity. Many people probably have mild cases that will never be diagnosed, but morning back pain may be the tip of that iceberg — the most likely time and place for the symptoms to be felt, even if you are otherwise mostly fine.

What do you do about trigger points and fibromyalgia?

Those are both big, separate topics, but there are many resources on where you can get started. Self-massage and heating are by far the best (cheap, safe) ways to start working on muscle knots. Fibromyalgia is much more complicated, but the basics are sleep improvements, lots of light but thorough exercise, and learning about sensitization and the weirdness of pain.

Chronic low-grade inflammation and “inflammaging”

Everyone over 40 knows that it gets more uncomfortable to get out of bed as we age. Most people chalk it up to “arthritis,” but that’s rarely a significant factor until much later in life.6 Conditions like fibromyalgia and myofascial pain syndrome, as common as they are, can’t account for all of it. So what’s the problem?

A little bit of inflammation spread all over the place is a likely culprit. This might happen as a consequence of “metabolic syndrome,” [NIH] a set of biological dysfunctions strongly linked to poor fitness, obesity, and aging, and possibly linked to severe chronic stress as well.7 And aging itself seems to be inflammatory (no matter how fit, skinny, and calm you are), which is known as “inflammaging.”8 So, if you’re on the far side of middle age, or you’re younger but struggling with your weight and/or major long-term stress, chronic inflammation could be your issue.

But can this explain either morning pain or back pain specifically? The morning connection isn’t much of a reach: for whatever reason, inflammatory diseases are notoriously morning-o-centric (like inflammatory back pain mentioned above), and so it’s reasonable to assume that less serious inflammation has a thing for the morning too. We also know — only just recently — that the body can suppress inflammation at night, pumping out an anti-inflammatory protein on a schedule,9 which can almost certainly accounts for some morning pain and stiffness as the suppression wears off. No one knows anything about how to actually control that effect, but at least we know it exists.

The back connection specifically is trickier. Being overweight is definitely a risk factor for back pain,10 but not nearly as much as you might think. And many people may have metabolic syndrome due to stress… not obesity.

Still, the connection between being creaky in the morning and getting older is strong, and back pain is so common, that it’s not surprising that they would all intersect in many people.

What can you do about inflammation and inflammaging?

No one really knows, but fitness is undoubtedly critical — it’s the closest thing we have to a miracle drug or a fountain of youth. It’s also possible to some extent to eat an “anti-inflammatory” diet — which really just means a healthy diet, particularly one that doesn’t give our system major blood sugar regulation challenges. Fasting and ketogenic diets may also be worth experimenting with. Working on anxiety and major sources of chronic stress (like insomnia) is important too. And of course you should consider quitting any habits that are putting a strain on your biology, like smoking (of course), or drinking too much too regularly (more than a couple per day).

Nighttime tissue stagnancy

Being still is inherently uncomfortable. We like to move, and sitting or lying down always gets uncomfortable in time. Forced immobilization is a potent torture method. Working in stagnant postures — like sitting in at a desk, no matter how well we do it — can start to feel more like a kind of torture as we age.

Sleeping is another obvious source of tissue stagnancy, of course, but beds are more comfortable than chairs in every way, physically and psychologically. Healthy young people are relatively immune to this. But as we age and develop assorted vulnerabilities and sensitivities — things like fibromyalgia, myofascial pain syndrome, and chronic inflammation from metabolic syndrome, or just age itself — it starts to become a problem.

Trigger points in particular may be aggravated by stillness.11 Morning pain could a wake-up call (ha ha), letting you know that you have a bumper crop of mostly asymptomatic (“latent”) trigger points that flare up overnight. In Lita’s case, trigger points could account for the consistency of her symptom timing, and for the peculiar way in which she is fine at 6am, yet can’t stay in bed past 7am, but then is fine again by 8am as she gets moving and her trigger points calm down.

Why does sleep actually help some people? Sleep is generally regarded as regenerative, and not everyone’s back pain gets worse at night! There are many possible reasons for a night that actually helps low back pain. Some people just “sleep well” — they naturally and easily assume and maintain more comfortable sleeping positions, and change positions at good intervals. Some people may have mattresses and pillows and other sleep gear that facilitate this. And/or sleep may constitute such a significant and important period of relief from emotional stress and anxiety that this outweighs other factors. Younger people are generally much less vulnerable to tissue stagnation (they are better at maintaining their circulation despite stagnancy), and so they are better candidates for pain-free sleeping. Getting the idea? There are many variables. If you get a few good ones lined up, you may have no problem with back pain at night.

Postural strain

Stillness alone can eventually start to hurt, no matter how comfortable you are. But what if you’re uncomfortable? What if you’re not just still for a long time, but in a really awkward position? Awkward positions can hurt, and sleeping often involves slightly awkward positions held for periods long enough to cause sustained compression, pinching, and oxygen starvation of tissues (which may or may not have already been vulnerable or irritated).

The dose makes the poison: it doesn’t have to be an obviously bad posture to cause trouble. Just a little awkwardness will do the job if you’re stuck that way for long enough. Although people can also carelessly tolerate postural strains while wide awake, we’re much more likely to do it at night.

Minor injury (or re-injury)

We may also cause minor injuries in our sleep, or aggravate existing minor injuries and vulnerabilities (like chronic minor back pain). Sometimes you just roll over and pinch something hard enough and quickly enough to hurt it — maybe not even enough to wake you up, but enough to feel the consequences when you do wake up. Usually this is going to be an isolated incident, but what if you keep pissing off the same vulnerable tissue?

For instance, suppose you already have minor intermittent back pain related to an old accident: it’s bothered you for years, off and on, and you’ve learned that leaning backwards is usually bad news. But then you do it in the middle of the night in your sleep, an extended lumbar spine for an hour when you weren’t even conscious — no fair! And so you wake up in moderate pain.

In other words, whatever is bothering your back in the first place can be easily and routinely aggravated — re-injured — by common sleeping positions.

I have no personal experience with back pain like this, but I know exactly what this is like from trying to sleep with a shoulder injury.12

Such incidents won’t explain all chronic, consistent morning back pain, because you’re unlikely to slightly but frequently re-injure yourself in the same way. Or maybe it’s not so unlikely: if bending your spine one way or the other is a problem, it might be easily avoided during the day, but happen to some degree most nights. Again, it’s the duration that’s the issue.

Is there such a thing as “bad posture” when sleeping?

If you know that a sleeping position is uncomfortable for you, but you keep sleeping like that, that’s bad posture.

Sleeping position is clearly a factor in some back pain. Just about the only study ever done on this topic showed a small improvement in a few back pain patients who were “instructed regarding the recommended way to sleep” — which basically meant a more neutral position.13 The benefit was real but small. I think position is a minor factor in low back pain, and tough to fix unless there’s an obvious terrible position to avoid. Usually we don’t even suspect a problem with our sleep posture until it’s too late! For most people, trying to work on sleeping position probably does not offer particularly good bang for buck.

The most likely position to cause trouble is face down. I do not think that sleeping face down is a universally evil sleeping position — I am not on that bandwagon. But, based on years of anecdotal reports from clients and readers, I do think face-down sleeping does tend to bug lots of backs.

We can do a little to minimize the chances of an awkward position, mainly by starting out as comfortably as we can, and adding a little bracing with pillows to discourage too much rolling around. Using a knee pillow is the best example of this: just put an extra pillow between your knees while lying on your side. This reduces rotation in the spine, and rolling face down. Unfortunately, most people who toss and turn can make short work of any pillow arrangement in their sleep. Any pillow that’s in my way is kicked off the bed in about five minutes.

Mattress and pillow changes and upgrades

There world is full of claims about better mattresses and pillows, and of course most of it is wishful thinking. There are so many subjective variables in what constitutes “comfortable” that it is probably impossible to objectively define the “best” mattress or pillow. It’s also actually impossible to really know our own preferences, because you really can’t know how comfortable a mattress is without sleeping on it for a couple weeks. You’d have to buy a series of mattresses and take some really careful notes on your sleep quality, and even then there could be many factors that would spoil it. Testing pillows is a little more economically and logistically feasible, but not much.14

There is a little evidence that a new mattress can improve back pain.15 A small study found that back pain was worse for people with the cheapest and oldest mattresses, and improved when they got better new mattresses. The difference was not dramatic, but worth noting, and undoubtedly worthwhile. If insomnia or the sleep disturbances of fibromyalgia are part of your problem, it’s probably a good idea to optimize anything you can.

The anti-nap: take a sleep break

Here’s one weird, good trick: if you’re really struggling with night and morning pain, break up the night. Just like you need breaks from long stretches of sitting, you may need to take a break from sleeping.

If you’re actually sleepless and in pain, don’t stay in bed squirming in misery all night — get up and help yourself! Or if you are sleeping, set an alarm! Either way, get out of bed, and mobilizations, heating, or self-massage your back — or whatever else you’ve ever found helpful. Or ignore your back and do something pleasant.

If you were in an awkward position when the alarm went off, you may really be doing yourself a favour by interrupting it. You can “reset” your sleeping position when you go back to bed.

Few people have ever thought of trying this, let alone taken it seriously, or tried it consistently for a few nights. There’s an understandable emotional reluctance to interrupting sleep for the sake of doing therapy on yourself — we’re all over-tired, and that’s an issue too — but it may well be the lesser of evils, if sleeping is hurting your back.

Stranger still, it may even be unhealthy (as well as painful) to try to sleep all the way through every night. There is actually a natural wakeful period in the middle of the night, like a mirror image of afternoon naps, which most modern people are resisting — we think we’re supposed to be asleep all night!16 But that natural tendency to wake up for a bit may actually exist to prevent excessive tissue stagnancy! So try not fighting it for a while — you don’t have to do it every night, or forever. If it helps you get through a rough patch with your back, it’s certainly worth a shot. And it’s worthwhile if it helps you sleep when you go back to bed!

Final tip: try getting up and taking care of your back for a few minutes without turning on a light — staying in the dark will help preserve “sleep mode.”

Psychological factors?

Probably not. The book Back Sense proposes that morning back back is caused by “stressful night-time mental patterns manifesting as back pain.” I do not dismiss the role of psychology in back pain — quite the opposite! it’s a major theme in my writing about back pain.

But I think that author is indulging in a simplistic mind-body connection theory. I’ve written crankily about this kind of logic elsewhere (see Why Do We Get Sick? or Pain is Weird). It’s a bit of a reach to say that you have such a problematic, pain-causing mental state like clockwork every morning between 6am and 7am exclusively. Applying How to Simplify Chronic Pain Puzzles to the problem, it is much (much!) more likely that there is simply a time limit on how long you can lie in bed without tissue crankiness.

What about nocturnal intervertebral disc swelling?

Between every pair of vertebrae is a bit of padding, the infamous disc. They probably swell up a wee bit overnight. There are two studies that suggest this1718 (although one of them was a study of long term bed rest, and only barely applicable here). A 2016 paper speculates that that disc swelling is why astronauts probably suffer from more disc herniations than they should.19 Weightlessness is undoubtedly like resting your spine, but it’s another long-term effect, so I’m not sure how relevant the astronaut angle is — it’s just a fun angle on the topic.

I saved this idea for last because it’s too speculative to be really satisfying.

Discs may swell, but that doesn’t mean swelling discs hurt. Mild swelling is hardly a concern in itself, and most people don’t wake up in pain, so it’s unlikely that swelling alone is a problem. Swollen discs may hurt more in the morning if there’s already something wrong with them, such as annular tears,20 but such discs might well be uncomfortable regardless. Mildly herniated discs might swell and effectively be more herniated in the morning — but many herniations are painless, so that’s hardly a smoking gun.

It’s an interesting possibility that nocturnal disc swelling is a factor in morning back pain, but the truth is beyond our reach. For all we know, problems with discs might be much more aggravated by postural strain… or it could be a complicated combination, such as swelling that is exaggerated by postural strain but still only hurting when other problems are present.

About Paul Ingraham

Headshot of Paul Ingraham, short hair, neat beard, suit jacket.

I am a science writer, former massage therapist, and I was the assistant editor at for several years. I have had my share of injuries and pain challenges as a runner and ultimate player. My wife and I live in downtown Vancouver, Canada. See my full bio and qualifications, or my blog, Writerly. You might run into me on Facebook or Twitter.

Related Reading

What’s new in this article?

Nine updates have been logged for this article since publication (2007). All updates are logged to show a long term commitment to quality, accuracy, and currency. more When’s the last time you read a blog post and found a list of many changes made to that page since publication? Like good footnotes, this sets apart from other health websites and blogs. Although footnotes are more useful, the update logs are important. They are “fine print,” but more meaningful than most of the comments that most Internet pages waste pixels on.

I log any change to articles that might be of interest to a keen reader. Complete update logging of all noteworthy improvements to all articles started in 2016. Prior to that, I only logged major updates for the most popular and controversial articles.

See the What’s New? page for updates to all recent site updates.

Minor science update: interesting new citation about evidence of inflammation suppression at night (Hand et al).

Huge upgrade: completely rewrote almost everything about trigger points and added much more about fibromyalgia; revised everything about tissue stagnancy, postural strain, and sleeping position; added an important large new section about inflammation and “inflammaging”; added a minor new section about mattresses; added several more specific tips and suggestions.

Added some information about fibromyalgia and some other causes of non-back morning pain.

Edits and elaborations for new nocturnal disc swelling section.

New section: “What about nocturnal intervertebral disc swelling?”

More editing, clarifying the idea of postural strain at night: “the dosage makes the poison.”

Editing for clarity and readability, first half. More information about the vulnerability of the paraspinals to trigger points. New image of a messy bed.

Major revision: a new structure for the article. It’s now built around three possible causes of morning back pain. Modernization of trigger point information as well.

An important update: added a whole bunch of new information about inflammatory back pain. It’s absence in previous versions of the article was a major oversight.



  1. Morning pain and stiffness is a symptom of several common conditions, including fibromyalgia, osteoarthritis, rheumatoid arthritis, plantar fasciitis, Achillis tendonitis, and carpal tunnel syndrome. (Most repetitive strain injury are probably worse in the morning, but it’s more obvious with some than others.) Most of these do not primarily affect the back, however. BACK TO TEXT
  2. IBP and spondyloarthritis umbrella concepts for several other rheumatic (inflammatory) diseases, including ankylosing spondylitis, reactive arthritis, psoriatic arthritis, inflammatory bowel disease-related arthritis. There are also cases that can’t be classified: “generic” spondyloarthritis. Although it develops slowly, this is one of the rare scary causes of back pain. You don’t want this diagnosis. BACK TO TEXT
  3. Arnbak B, Hendricks O, Hørslev-Petersen K, et al. The discriminative value of inflammatory back pain in patients with persistent low back pain. Scand J Rheumatol. 2016 Mar:1–8. PubMed #26982485. 82% of more than 700 patients with chronic low back pain reported “morning stiffness” — practically everyone! — but only 11% actually had spondyloarthritis (according to ASAS criteria). Only 10% felt that their pain was worst in the morning. Although these and other inflammatory back pain signs were significantly associated with spondyloarthritis, there’s just too much overlap with other kinds of back pain for morning symptoms to actually identify spondyloarthritis. BACK TO TEXT
  4. If indicated, a doctor can get you checked out for other signs, like blood tests that show elevated CRP, and/or the presence of a particular gene, HLA-B27. An MRI can also help diagnose this kind of inflammation.

  5. In my back pain tutorial, I get into some of the possible reasons why trigger points seem to favour the back. No one really knows what it’s about, but it’s certainly a thing. Ask any massage therapist: we get a lot more requests for back massage than, say, upper arm or abdominal massage. BACK TO TEXT
  6. Not many middle-aged people have enough arthritis to account for the sheer number of variety of aches and pains that they often report. Arthritic pain is typically well localized to specific joints, and usually not serious in middle age unless the joint is vulnerable to early arthritis due to an injury. BACK TO TEXT
  7. Prolonged chronic stress can probably contribute to metabolic syndrome (Gohil et al) by messing with the hormonal balance of the hypothalamic-pituitary-adrenal axis (HPA-axis). BACK TO TEXT
  8. Franceschi C, Campisi J. Chronic inflammation (inflammaging) and its potential contribution to age-associated diseases. J Gerontol A Biol Sci Med Sci. 2014 Jun;69 Suppl 1:S4–9. PubMed #24833586. PainSci #53291. “Human aging is characterized by a chronic, low-grade inflammation, and this phenomenon has been termed as "inflammaging." Inflammaging is a highly significant risk factor for both morbidity and mortality in the elderly people, as most if not all age-related diseases share an inflammatory pathogenesis. Nevertheless, the precise etiology of inflammaging and its potential causal role in contributing to adverse health outcomes remain largely unknown.” BACK TO TEXT
  9. Hand LE, Hopwood TW, Dickson SH, et al. The circadian clock regulates inflammatory arthritis. FASEB J. 2016 Aug. PubMed #27488122. This research describes a protein, cryptochrome, used by the body’s “biological clock” to represses inflammation during the night, strongly suggesting that inflammation probably varies in a daily rhythm controlled by the brain. “The clinical implications are far-reaching,” said Thoru Pederson, Ph.D., Editor-in-Chief of The FASEB Journal. BACK TO TEXT
  10. Wright LJ, Schur E, Noonan C, et al. Chronic pain, overweight, and obesity: findings from a community-based twin registry. J Pain. 2010 Jul;11(7):628–35. PubMed #20338816.

    Does it hurt to be heavy? It seems possible, and in this study “obese twins were more likely to report low back pain.” But it’s not that simple: there are many variables involved. For instance, several other pain problems were also more likely: “migraine headaches, fibromyalgia, abdominal pain, and chronic widespread pain.” Weight is associated with more pain in general, not low back pain specifically, as you’d expect if the problem were simply due to compression of the spine. Clearly that typical assumption is not a safe one, and indeed the apparent connection between weight and pain weakened when the data were adjusted for common denominators like depression, a strongly confirmed risk factor for low back pain. In other words, if you factored out the depressed cases, the remaining subjects were not all that likely to have back pain. Given such complexity, the researchers made it clear that more and different research is needed to figure out what, exactly, is causing what. No kidding!

  11. There’s no direct evidence for this. It’s a claim that has often been made my clinicians and experts on the topic. Although no one knows exactly what makes trigger points flare up (or go away), extremes of activity and stimulation — too much and too little — are plausible possibilities that seem to be consistent with what patients often report. BACK TO TEXT
  12. I ripped up my shoulder joint playing ultimate (a Frisbee sport). It was hard to sleep for most of a year. When I did sleep, I routinely rolled onto the injured shoulder. Sometimes it woke me up; if it didn’t, I’d wake up with my shoulder howling. And then it would calm down and be mostly fine for the rest of the day. I knew exactly why I had morning shoulder pain, but what if my shoulder was vulnerable for some less obvious reason? I might have thought I had unexplained “morning shoulder pain.” BACK TO TEXT
  13. Desouzart G, Matos R, Melo F, Filgueiras E. Effects of sleeping position on back pain in physically active seniors: A controlled pilot study. Work. 2015;53(2):235–40. PubMed #26835867. BACK TO TEXT
  14. A few years ago, I got keen on trying to figure out “once and for all” what kind of sheets I really like. I bought several sets of sheets of different kinds and qualities, including some expensive ones. Despite the expense and the effort, the experiment was a failure: I wasn’t organized enough, and simply couldn’t keep track of the relatively subtle differences between sheets. But I did at least learn that I have no obvious preference for premium sheets. 😉 BACK TO TEXT
  15. Jacobson BH, Boolani A, Dunklee G, Shepardson A, Acharya H. Effect of prescribed sleep surfaces on back pain and sleep quality in patients diagnosed with low back and shoulder pain. Appl Ergon. 2010 Dec;42(1):91–7. PubMed #20579971. BACK TO TEXT
  16. The science:

    We often worry about lying awake in the middle of the night — but it could be good for you. A growing body of evidence from both science and history suggests that the eight-hour sleep may be unnatural.

    Indeed, all the research indicates that humans aren’t actually built to sleep through the night (with the exception of my wife, apparently, who can sleep 10 hours without so much as rolling over). The wakeful patch tends to occur between about 2–4. I discuss this more in my insomnia tutorial.

  17. Matsumura Y, Kasai Y, Obata H, et al. Changes in water content of intervertebral discs and paravertebral muscles before and after bed rest. J Orthop Sci. 2009 Jan;14(1):45–50. PubMed #19214687. BACK TO TEXT
  18. Belavý DL, Miokovic T, Armbrecht G, Felsenberg D. Hypertrophy in the cervical muscles and thoracic discs in bed rest? J Appl Physiol (1985). 2013 Sep;115(5):586–96. PubMed #23813530. BACK TO TEXT
  19. Belavy DL, Adams M, Brisby H, et al. Disc herniations in astronauts: What causes them, and what does it tell us about herniation on earth? Eur Spine J. 2016 Jan;25(1):144–54. PubMed #25893331. “The most likely cause for lumbar IVD herniations was concluded to be swelling of the IVD in the unloaded condition during spaceflight.” BACK TO TEXT
  20. Annular tears or basically arthritic fissures in the disc — splitting like chapped lips. “Annular” because the lesion is in the annulus fibrosis, or outer layer of the disc. BACK TO TEXT