If you’re reading this article, chances are your back pain is bad — so bad that it’s disrupting your ability to sleep well, which generally makes everything in life worse. Poor sleep can exacerbate pain symptoms, affect daytime fatigue, and contribute to a host of other health problems, from heart disease to weight gain to diabetes.
It’s an important first step that you’re taking your back pain at night seriously and looking for answers as to what is causing it.
Back pain at night could be due a number of different health concerns (more on that below), but one that often goes overlooked is inflammatory back pain from conditions like ankylosing spondylitis or axial spondyloarthritis (AS). These are types of arthritis that affect your spine and other parts of the body, causing inflammation, chronic pain, and, over time, joint damage that can cause the bones in your spine to fuse together.
In a study presented at the 2018 annual meeting of the American College of Rheumatology, morning stiffness and pain that wakes people up from sleep were the two most common symptoms in people with back pain from inflammatory arthritis like AS.
Back Pain at Night and Ankylosing Spondylitis
There are two main categories of back pain: mechanical and inflammatory. Mechanical back pain results from problems with the way the different components of your spine (joints, discs, muscles, tendons and ligaments, etc.) work together. Mechanical back pain, such as from overuse injuries, poor posture, or a herniated disc, is the reason for the vast, vast majority of back pain cases.
On the other hand, inflammatory back pain occurs because there’s a problem with your immune system attacking the joints in your spine, sacroiliac joints (where the spine connects with the pelvis), and the entheses (the connective tissue between ligaments, tendons, and bones).
Back pain that wakes you up in the second half of the night is one of a few key signs that your back pain could be inflammatory and due to a disease like ankylosing spondylitis.
“Patients often experience stiffness and pain that awakens them in the early morning, a distinctive symptom not generally found in patients with mechanical back pain,” reports Medscape.
“It’s not common to have back pain so bad in the middle of the night that you can’t go back to sleep,” says Fardina Malik, MD, a rheumatologist at NYU Langone in New York City who frequently treats patients with ankylosing spondylitis.
Mechanical back pain generally feels better when you rest or sleep. You might have discomfort, but you should be able to sleep through the night.
If you have inflammatory back pain, however, rest makes it worse. While you sit still for too long, such as during sleep, inflammatory chemicals accumulate in your joints, exacerbating pain and stiffness. That’s why people with inflammatory back pain can wake up in agony in the middle of night and feel stiff and achy first thing in the morning.
Other Signs of Inflammatory Back Pain
Back pain at night is one of the more obvious clues for inflammatory back pain, but there are other key signs to keep in mind as well. There are slightly different sets of criteria for inflammatory back pain, but generally speaking they include the following:
- Back pain at night
- Back pain improves with exercise or activity
- Back pain gets worse with rest
- Back pain in the morning that lasts more than 30 minutes
- Gradual, not sudden, onset
- Lasts more than three months
- Symptoms first occur before age 40-45
- Alternating buttock pain
- Anti-inflammatory meds (NSAIDs) help you feel better
Here’s how a New England Journal of Medicine article describes inflammatory back pain: “Such pain is usually dull and insidious in onset and is felt deep in the lower back or buttocks. Another prominent feature is morning back stiffness that lasts for 30 minutes or more, diminishes with activity, and returns after inactivity. Although initially the back pain is intermittent, over time it becomes more persistent. Nocturnal exacerbation of pain is common, particularly during the second half of the night, forcing the patient to rise and move around.”
If you have back pain at night but don’t recognize many of these other signs of inflammatory back pain, your symptoms may not be from ankylosing spondylitis, but rather because of different reasons for nocturnal back pain.
Do Doctors Recognize Nighttime Back Pain as an AS Symptom?
Unfortunately, not as much as we’d like. According to a study of 300 British primary care doctors, only 5 percent could identify all of the common features associated with inflammatory back pain. Only about two-thirds of doctors in the study knew that back pain at night was associated with inflammatory back pain.
“I started to develop back pain in my twenties at night and I always thought that it was from a workout,” says Hillary Norton, MD, a Santa Fe-based rheumatologist who was diagnosed with ankylosing spondylitis during her medical training.
“I’d have trouble moving at night and when it got scary enough that I finally sought answers I saw a sports medicine doc, who misdiagnosed me with an SI joint sprain,” she says. “I’m not sure if such a thing exists actually, but every time I went on the internet, like many patients do when you can’t stay in bed at night, I never found information that was really helpful in leading me to the correct diagnosis.” (Watch more of Dr. Norton discussing ankylosing spondylitis in this video.)
Other Causes of Nighttime Back Pain
Nighttime back pain isn’t always a sign of a serious disease, especially if it happens infrequently or for a short period of time. It’s when nighttime back pain becomes a chronic problem that you need to get it checked out and properly diagnosed. Possible reasons for nighttime back pain aside from inflammatory arthritis like AS include:
- Injuries to the spine, such as a sprain or fracture
- Spinal bone infection
- Neurological conditions
- Spinal tumors (keep in mind that while most people with spinal tumors have back pain, most people with back pain do NOT have spinal tumors)
What to Do Next
Nighttime back pain that wakes you up from sleep or prevents you from getting a good night’s sleep is a red flag you need to discuss with your doctor. Seeing your primary care doctor is a good place to start.
Make sure to familiarize yourself with the symptoms of mechanical vs. inflammatory back pain, as well as other symptoms of ankylosing spondylitis, so you can be sure to have a proactive discussion about whether your back pain at night could be inflammatory.
If your primary care doctor suspects it could be, you should be referred to a rheumatologist for more testing.