Knee Pain When Lying Down On Side | 5 Possible Causes

Written By on July 14, 2022 — Medically Reviewed By Kris Ceniza (PT)

Written by on July 14, 2022 — Medically Reviewed By: Kris Ceniza (PT)

omeone lying down on their side grabbing their knee in pain

You’re finally home at the end of the day, and there it is – that annoying knee pain when lying down on your side. What could it be? More importantly – what can you do about it?

Most of the time it’s something benign – your body begging for more physical activity. Other times, however, it can be something more challenging to treat. Like ITBS, PFPS, or bursitis.

But don’t worry, we’ll cover the most common causes and their treatments below. These are the topics discussed, tap on any of them to easily navigate through the article:

5 causes of pain on the side of your knee joints while lying sideways

1) You’re not moving enough

Pain is a tool our bodies have to communicate. It tells us when we’re injured, when we’re moving too much, and yes – when we’re not moving enough.

You see, apart from helping us move around, muscles also pump blood throughout our limbs. One of the many benefits of this is keeping our joints lubricated and healthy.

But, in a sedentary lifestyle, the liquid inside our joints stagnates.

This lack of movement can cause joint soreness at the end of the day.

Remaining sedentary makes this knee pain worse. Your muscles will get weaker after a while, thus pumping less blood and fluids, putting you in this vicious cycle of pain.

In the long term, this also increases your risk of heart disease and other chronic conditions. (1)

What can you do about it?

The good news is that it’s an easy fix.

Include regular exercise during your day. Start by walking a little more – this free app from the NHS called “Active 10” can get you started.

Knee Force Knee Sleeve

If you have nighttime knee pain, you can also try tai-chi, yoga, or pilates – these are great options for starters.

And, if you’re short on time, start with one or two low-impact exercises, like glute bridges or air squats.

More exercises: Strengthen your knees with these 6 effective exercises

2) Knee osteoarthritis

Knee osteoarthritis is the wear and tear of our knee bones. Although some people with this diagnosis don’t have symptoms, the ones that do often feel (2):

  • Painful swelling on the affected joint.
  • Stiffness.
  • More pain while resting.
  • Sleep disruptions due to knee pain in severe cases.

This knee arthritis pain can be like the one from rheumatoid arthritis (RA), but they’re entirely different conditions. RA is an autoimmune disease that often affects several joints at once.

With that said, they can have similar symptoms, including knee pain while lying on your side. So, it’s key to have a proper diagnosis to make sure you get the right treatment.

Learn more: Diagnostic process of knee osteoarthritis.

What can you do about it?

This is believed to be the most common cause of knee pain in adults over 50. Thus, there are tons of studies looking for ideal treatments.

Most solutions focus on lifestyle changes. Like maintaining a healthy weight, or getting into a weight-loss program if you’re overweight.

These changes are extremely effective regardless of the severity of the osteoarthritis.

But, if you’re looking for more immediate pain relief, check the “treatments” section below.

Keep reading: How to treat knee osteoarthritis?

3) Runner’s knee

This is also known as “patellofemoral pain syndrome.” Although it’s common in runners – thus its name -, it’s also seen in people that sit for long periods due to their jobs.

The pain is often on the kneecap area but can radiate to the sides of the knee. It can get worse after standing, walking, or climbing stairs. The discomfort can be present while resting, too. (3)

The tell-tale sign is if you experience pain in your knees while sitting.

What can you do about it?

If you’re an athlete, go to a physical therapist. They will assess your movement patterns to address the cause of pain so you can enhance your performance.

But, if the pain is associated with sitting, you’ll improve massively by taking movement breaks. At least every hour, stand up, walk a little for a minute or two, or do some light stretches.

You can set a 1-hour timer on your phone as a reminder. I personally do this and it’s been a game-changer for my knee health. The Pomodoro technique is also effective for this.

4) Iliotibial band syndrome

anatomical view of the IT band

The iliotibial band is a thick, strong tissue on the outer side of your leg. It starts at the side of your hip and ends below the knee joint.

Now, the iliotibial band syndrome (ITBS) is a term we use to describe pain related to this tissue. It’s common in running athletes, cyclists, and basketball players. (4)

Knee Force Knee Sleeve

Common symptoms include a burning knee pain on the side of the joint while walking, running, or at rest. The knee pain can worsen while kneeling as well.

What can you do about it?

First, it’s key to rest. ITBS is common in athletes with a sudden increase in training intensity. If that’s you, focus on sleeping at least 7 hours each night to help your body heal.

Another popular tool is foam rolling. Although studies haven’t found relevant benefits from this, it can provide pain relief to some people. (5)

In any case, the treatments below are effective at helping to calm inflammation and reduce pain.

5) Knee joint bursitis

Bursae are fluid-filled sacs between tendons, muscles, skin, and/or bone. They reduce the friction between tissues, keeping our joints healthy and moving smoothly.

Now, bursitis happens when any of these bursae have inflammation. This can be due to infection, excessive movement, or uric acid build-up, among other things.

There are several types of knee bursitis and most of them improve with rest. But, the pain gets worse if you put pressure on them.

So, if you have bursitis on the inner or outer side of your joint, you will have knee pain if you lay on your side.

What can you do about it?

Bursitis looks like a swollen, red lump on your knee. If you have one, please go to the hospital. This is crucial because your doctor needs to know if it’s infected or not so you can get the right treatment.

In case it’s infected, your doctor will prescribe antibiotics – they will alleviate pain pretty fast. If it’s not, he/she will give you some home treatments and refer you to physical therapy. This will prevent a future episode of bursitis.

Further reading: Treating knee bursitis with physical therapy.

Treatments for side knee pain while lying down

someone in a physical therapy setting, doing exercise

Hot/Cold therapy

Hot therapy with heat packs can soothe aching joints. It increases blood flow and gives a feeling of relaxation. This is particularly effective for osteoarthritis.

But, if you need to reduce swelling or have a fresh injury, ice can be better. Apply it on the area for 10 minutes tops, 2 or 3 times per day for best results.

Learn more: What’s better for arthritic knees – hot or cold?

Visit a physical therapist

A physical therapist will be your best ally during recovery. After assessing your current situation, they will design a treatment plan so you can overcome the pain and return to your lifestyle.

Their treatment provides initial relief, prevents further damage, and gets you back on track. Sessions often include strengthening exercises, stretches, and passive modalities.

Wear a knee brace during the day

According to studies, knee braces can provide relief, help you move more, and boost your healing process. (6)

But, the infinite variety of knee supports is both a blessing and a curse. It’s great to have so many options, but it’s hard to choose. If in doubt, refer to the advice of your doctor or physical therapist.

Learn more: The different types of knee braces and what you need

Corticosteroid injections

Here, a doctor injects a medication that can reduce pain and swelling in the short term, for up to 4 weeks. This is an option for people with severe knee pain that impairs their daily life. (7)

They can be an effective tool for reducing pain during flare-ups like those in osteoarthritis. But they can be risky as well. They can cause infections on the site, atrophy, and other side effects when not administered properly. (8)

Please, talk to your doctor first and make sure you go to one that you trust. Learn about the risk of corticosteroid injections and other treatment options available.

Knee replacement

This is the last resort for people with knee osteoarthritis. Here, an orthopedic surgeon will perform a joint replacement. This can reduce joint pain totally or partially in a high percentage of people with severe degeneration. (9)

This can help: Is it time to get knee osteoarthritis surgery?

Tips to relieve knee pain at night

woman sleeping with a knee pillow

There are several effective ways to relieve knee pain at night, but the most effective during a fresh injury or a pain flare-up are:

Practice good sleep hygiene

This can be as simple as having a bedtime routine, taking a warm bath before going to bed, or doing gentle exercises to help you relax.

Other times, though, you may need to get a more supportive mattress or use a knee pillow to be in a more comfortable sleep position.

Treating the underlying condition

This is the best way for preventing knee pain at night. A physical therapist can help you with that, or a sports medicine physician if you’re an athlete.


Can sleeping on your side hurt your knees?

It shouldn’t. Unless you have a previous knee injury, like a sprain, meniscus tear, bursitis, etc. In that case, sleeping on your side could make that injury worse.

Why does knee pain get worse at night?

Before sleep, our minds aren’t as distracted as during the day. So, we pay more attention to what we’re feeling in our bodies. The issue didn’t necessarily get worse; we simply get to be more aware of it.

Related: Why does knee OA pain worsen at night?

Conclusion: Causes of throbbing knee pain when lying on your side

Having a sore knee can be worrying. Even more so if it happens while lying down. But, most of the time, it is relatively easy to manage.

Look for professional medical advice if you’re not getting better after a few days. After all, you deserve a good night’s sleep.


  1. Daneshmandi, Hadi et al. “Adverse Effects of Prolonged Sitting Behavior on the General Health of Office Workers.” Journal of lifestyle medicine vol. 7,2 (2017): 69-75. doi: 10.15280/jlm.2017.7.2.69
  2. Sasaki, Eiji et al. “Nocturnal knee pain increases with the severity of knee osteoarthritis, disturbing patient sleep quality.” Arthritis care & research vol. 66,7 (2014): 1027-32. doi: 10.1002/acr.22258
  3. Bump J M, Lewis L. “Patellofemoral Syndrome.” Statpearls. Retrieved on November, 2021 from:
  4. Hadeed A, Tapscott DC. “Iliotibial Band Friction Syndrome.” Statpearls. Retrieved on November, 2021 from:
  5. Wiewelhove, Thimo et al. “A Meta-Analysis of the Effects of Foam Rolling on Performance and Recovery.” Frontiers in physiology vol. 10 376. 9 Apr. 2019, doi:10.3389/fphys.2019.00376
  6. Cudejko, Tomasz et al. “The immediate effect of a soft knee brace on pain, activity limitations, self-reported knee instability, and self-reported knee confidence in patients with knee osteoarthritis.” Arthritis research & therapy vol. 19,1 260. 1 Dec. 2017, doi:10.1186/s13075-017-1456-0
  7. Ayhan, Egemen et al. “Intraarticular injections (corticosteroid, hyaluronic acid, platelet rich plasma) for the knee osteoarthritis.” World journal of orthopedics vol. 5,3 351-61. 18 Jul. 2014, doi:10.5312/wjo.v5.i3.351
  8. Holland, Christian et al. “Septic and aseptic complications of corticosteroid injections: an assessment of 278 cases reviewed by expert commissions and mediation boards from 2005 to 2009.” Deutsches Arzteblatt international vol. 109,24 (2012): 425-30. doi:10.3238/arztebl.2012.0425
  9. Wylde, Vikki et al. “Persistent pain after joint replacement: prevalence, sensory qualities, and postoperative determinants.” Pain vol. 152,3 (2011): 566-572. doi:10.1016/j.pain.2010.11.023
Mitch Torres (PT)
Mitch is a physical therapist, personal trainer, and nutrition coach. Fascinated with the knee joint, Mitch poured that passion into writing about knee pain and how to overcome it with movement. His goal is to teach you how to apply this knowledge into your daily life, so you can keep knee pain away for good.