Which comes first? Does pain cause sleep issues? Or does poor sleep cause pain? There’s no question I hurt more when I don’t sleep well. Getting just a few extra hours on weekends makes a huge difference in how I feel throughout the day. According to the National Sleep Foundation, the impact of pain-related sleep loss on millions of Americans is far-reaching. As we discussed last week, it affects our emotions, thinking, health, and eating habits. Now let’s explore how pain and sleep interact.
It is especially important given that so many Americans suffer from chronic pain and sleep disorders. A 2015 Sleep in America poll found that over half of Americans experience pain while trying to sleep. The term “insomnia” includes all types of sleeping problems, such as difficulty falling asleep, difficulty staying asleep, and waking up earlier than desired. Of all medical conditions, pain is the number one cause of insomnia.
According to a 2007 article in Arthritis Today, most adults need between 7 and 9 hours of sleep nightly (as we discussed last week). The article goes into detail describing the sleep cycles as roughly 90-minute segments. We start out in stages 1 and 2, in non-REM (rapid eye movement) sleep, then we enter stages 3 and 4 which are deeper, more healing and renewing stages. The fifth segment is our deepest sleep when REM sleep occurs. This is the more restful state of sleep and the one in which we dream. After cycling through these five stages, we then do it all over again. The problems we face when we awaken with pain is that often, our deep healing sleep is interrupted, if achieved at all.
Michael Smith, PhD, Director of the Sleep Psychophysiology Lab at Johns Hopkins University in Baltimore, when discussing people in pain said, “Their deeper sleep is disrupted by arousals or outright awakenings. They may sleep 10 hours, but feel groggy and unrefreshed the next day.” Due to constant interruptions, people with chronic pain have trouble falling asleep, wake up frequently during the night, and often awaken early and can’t fall back to sleep. Many patients with chronic back pain don’t feel refreshed when they wake up in the morning, a sleeping problem termed “non-restorative sleep.” It is the result of them not reaching the later, much needed stages of sleep before waking up. This hampers the body’s immune response and can also affect cognitive function. Thus, a vicious cycle develops in which the pain disrupts one’s sleep, and difficulty sleeping makes the pain worse, which in turn makes sleeping more difficult.
Most of us with chronic pain issues know exactly what Dr. Smith is saying. There have even been studies showing that sleep deprivation in healthy individuals causes pain. One was from UCLA in 2006 where they evaluated 30 healthy individuals. It found they had chemical changes after they were kept awake from 11p.m. to 3 a.m., for just one night. Those changes included increases in inflammatory chemicals such as those the body produces in auto immune disorders. This caused increased pain sensitivity and actual pain in patients who do not even suffer from pain. Just imagine what lack of sleep is doing to those of us who already have chronic pain?
According to several articles in JAMA, another major driver of chronic pain in sleep deprivation is “central desensitization- basically turning up the volume on all pain receptors.” An internet survey of over 2,500 people suffering from fibromyalgia (a disorder characterized by widespread musculoskeletal pain that I will discuss in future posts) identified sleep deprivation as the most common aggravating factor for their pain. Another survey found a fairly spectacular statistic that 53% of chronic low back pain patients had insomnia, compared with only 3% in pain-free controls. A 2018 study went further abroad and looked at links between pain and severe sleep problems. The data set was large and the results significant – pain and sleep problems were strongly linked. People who hurt cannot sleep and vice versa – and that’s true globally.
But insomnia doesn’t just cause pain in general, and it doesn’t just do it by mucking with the volume of all your nerves. It causes pain in the muscles and skeletal system specifically. We know this because even in normal, healthy people, sleep deprived participants “reported more musculoskeletal symptoms” and “a significant increase in muscle tenderness.” Sleep-deprived subjects had a whopping “24% decrease in their musculoskeletal pain threshold.” That’s means they felt more tenderness specifically in their muscles. They showed an increased sensitivity to any touch or “mechanical” stimulation. 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 (non-opioid) analgesic compounds.” Now that’s impressive; next time don’t reach for an Aleve, reach for a pillow and get some sleep!
Clearly, sleep has a major influence on every aspect of our lives- emotional, physical as well as a multitude of health issues. When you think about it, something as easy to achieve as 7 hours of sleep a night could be that “magic pill” we’ve all been searching for to help diminish all our ills and transform our lives. Maybe it’s time we all took its restorative cure.