Here's a not-so-fun fact for ya: Research suggests that sleep deprivation makes you more sensitive to pain, and more pain means it's also harder for you to fall asleep. The good news is—strategic pillow placements can help dull down this brutal cycle. And that, of course, includes putting a pillow under your knees.
Generally speaking, placing pillows under your knees is good for you if it helps relieve your pain. Or, perhaps just as important, if it helps you avoid pain altogether.
In this article, I'll list down a few benefits of this pillow placement, who can reap these benefits, and who should avoid it completely.
3 Benefits of Sleeping with a Pillow Under Your Knees
Improves your spinal alignment
Human as we are, we have different preferences and different anatomies. We prefer different sleeping positions, use mattresses and pillows that vary in firmness and thickness, and have postures that might not be optimal.
Unfortunately, these preferences can also be why we sleep with (and wake up to) joint pain and stiffness.
Specifically for back sleepers, using a knee pillow helps put your spine in a more neutral position when you have an exaggerated curve. The slight elevation of your knees tilts your hips backwards which, in turn, neutralizes the curve of your spine.
Helps manage inflammation
In the medical field, it's common to find limbs with fresh injuries or inflammatory conditions being elevated. In this case, the knee pillows raise your knees (or your legs) above your chest which, in turn, uses gravity to promote blood flow back to your heart.
For fresh injuries, this helps minimize swelling and dull down pain. For inflammatory conditions, such as osteoarthritis and rheumatoid arthritis, the improved blood circulation helps manage the inflammation while you sleep.
Now, whether you need a wedge pillow or a long knee pillow depends on your condition or injury. Reach out to your doctor or physical therapist to see which of the two will work better for you.
Research argues that the foundations of health are exercise, diet, and a good night's sleep. Compromise one and it affects the other two.
Knee pillows come into equation for the simple reason that it improves sleep quality which, in turn, encourages recovery. This is especially true for athletes and those of you who live active lifestyles.
Admittedly, this isn't true for everyone. Many people catch their ZZZs fine without knee pillows. But for those of you who have trouble falling asleep, be it from hip or knee pain, poor sleeping posture, or even back pain, adding a knee pillow to your arsenal can be an easy solution.
Again, it's always a good idea to check with your doctor or PT to make sure it benefits you—which brings me to the next part of our discussion.
Conditions that Can Benefit from Under-Knee Pillows
Painful lumbar lordosis
Before I say anything else, everyone has a different "normal" posture. For instance, some are naturally more slouched than others. So, as long as your posture isn't painful or limiting you in any way, you're good.
That being said, some postures do cause pain. Specifically speaking, an excessive inward curve on your lower back (i.e. lumbar lordosis) can cause muscle spasms and nerve root impingements that can be debilitating.
As stated above, a pillow under your knees promotes a more neutral alignment of your spine while you sleep. This, in turn, can help correct the excessive lordosis, relax your muscles, soothe the pressure from your nerves, and provide pain relief.
Knee and ankle arthritis
This goes back to how elevating your legs controls inflammation.
With arthritis being an umbrella of inflammatory conditions accompanied by pain, the use of a knee pillow helps relieve pressure off of those joints while also encouraging good blood circulation.
For knee arthritis, rounded or cylindrical pillows might be better but triangular, wedge-shaped pillows work, too. For ankle arthritis (as well as heel spurs), look for a long leg pillow that raises both your knees and feet.
Acute leg injuries
These include the many kinds of ankle and knee sprains, calf strains, meniscus injuries, and others.
Acute (new) injuries will inevitably swell up and cause pain. This is a normal part of the healing process but excessive swelling can also delay your recovery. With the elevation from using a knee pillow under your legs, however, this can be managed.
If you have varicose veins, or other symptoms of venous insufficiency for that matter, you might benefit from sleeping with a pillow under your knees.
Again, the elevation helps pull blood away from your legs and back into your heart. Thus, assisting your veins on what normally should be their job.
P.S. If you're showing signs of venous insufficiency, such as varicose veins, leg swelling, or pain while walking, please see your doctor.
Who Should Avoid Sleeping with a Pillow Beneath Their Legs?
Stomach sleeping has been highly regarded as the worst sleep position for your spinal health.
For one, if you're sleeping on a soft mattress, your hips will drop into the foam and disturb the natural alignment of your spine. It's even worse if you turn your head to one side.
Adding a pillow under your knees in this case just isn't natural (and downright weird, to be honest) as it further exaggerates the curve of your lower back.
Try adding a flat pillow under your pelvis or stomach instead.
Side sleepers, on the other hand, fare much better than stomach sleepers. But, adding a pillow under your knees here will also curve your spine to one side—and that comes with its own set of problems.
Instead, use hourglass or heart shaped pillows between (not under) your knees to improve the alignment of your pelvis and spine. A body pillow works, too.
First of all, knee pillows are great for pregnant women. Just not when you're putting the pillow under your knees.
This pillow placement implies that you're sleeping on your back which isn't the best position if you're already on your third trimester. The weight of your belly slows down circulation of the blood vessels behind your uterus which isn't great for your mini–me.
Try sleeping on your left side with a knee pillow between your knees instead. Although, it's still always best to consult with your doctor.
Is sleeping with a pillow under your knees bad for circulation?
When on a back-sleeping position, a leg pillow under your knees encourages good blood flow. It elevates your legs above your chest which, in turn, uses gravity to channel blood back to your heart.
Where should you place your pillow if you have knee pain?
That depends on the sleeping position you assume. For side sleepers, place the pillow between your knees. For back sleepers, directly under the knees will do the trick. Both placements will help keep your spine aligned and relieve pain and pressure points while you sleep.
For stomach sleepers, I recommend switching to side or back sleeping. Sleeping on your stomach, regardless of pillow placement, inevitably puts pressure at the front of your knees.
Why does putting a pillow under your knees help back pain?
Sleeping with a firm pillow underneath your knees helps hip and back pain because it simulates a more neutral spinal alignment. This, in turn, relieves pressure from herniated disc pain and pinched nerve roots, as well as relaxes excessively firing back muscles.
In a nutshell, knee pillows help improve the sleep posture of back sleepers, manage inflammation through gravity-assisted blood circulation, and maintain health through a more comfortable sleep.
Now, while it's generally a good idea, there are also cases where placing the pillows under your knees should be avoided. Pregnant women, in particular, may find it best to switch to side sleeping with a pillow between their legs rather than sleeping on their backs.