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This post contains four valuable tips for sleeping through the night following total knee surgery, so you don’t wake up in the middle of the night from knee pain.
In my capacity as a physical therapist, getting a good night’s sleep following total knee surgery is a common concern I hear from the hundreds of total knee surgery patients I have seen a day or two following their surgery.
Why Does Total Knee Surgery Pain Wake Me at Night?
The two most common reasons a new total knee surgery patient’s pain wakes them in the middle of the night are that their body is not producing enough endorphins and enkephalins to control the pain from about 2–3 a.m. until sunrise and poor knee sleeping posture.
Getting adequate sleep after a total knee replacement is a huge factor in the patient’s perception of pain after a total knee surgery.
The total knee replacement patients I see in their homes after total knee surgery frequently tell me they did not sleep well the night before, and I sometimes see this sleep disturbance pattern lasting for much longer than necessary.
After a couple of nights of not sleeping well, the patient will become increasingly irritable and desperate to get some sleep.
My experience treating patients with sleep disturbance after total knee surgery is that after about three nights of poor sleep, sleep deprivation is as much of a problem for the patient as the pain that is keeping them awake.
Tip 1: Apply Cold Therapy Before Going To Bed.
All of my total knee surgery patients are using either Ice Packs or Cold Therapy Machines (Amazon affiliate links) multiple times daily to help control pain levels. Applying cold therapy for 40 minutes just before going to bed will reduce your pain while sleeping
See my article: Ice After Total Knee Replacement: A PT’s Complete Guide.
Circadian Rhythm:
Endorphins and enkephalins are released on a circadian rhythm schedule.
The hippocampus is in charge of the internal 24-hour clock found in every person’s brain.
This circadian rhythm controls such things as the energy levels a person may have during different parts of the day.
Light and darkness are a couple of external influences that influence the circadian rhythm.
An example would be when the eyes recognize it is dark outside and inform the hippocampus that it is time to slow down a little. The hippocampus, upon receiving this information, signals the release of melatonin. The melatonin causes the person to become tired and prepares them for sleep.
That is what “jet lag” is all about. When the 24-hour cycle is interrupted by a period of significantly increased or decreased light, such as a long plane trip, that person can experience difficulty with sleep and awake times, sometimes taking several days to re-adjust to the current time zone.
Endorphins and Enkephalins:
Endorphins and enkephalins are two different five-amino-acid molecules produced by the human body and are distributed throughout the human body in the brain, nerve tissue, and some endocrine glands.
Endorphins and enkephalins are the body’s own painkillers and anti-inflammatory hormones.
The human body produces endorphins and enkephalins in a circadian rhythm.
They are released at sunrise, and enough is produced to last for about 20 hours on a “kind of” time-release schedule.
That means at about 4 hours before sunrise the body starts to burn through its supply of endorphins and enkephalins leaving the patient without their natural painkillers at about 2-3 o’clock in the morning.
And that is what my total knee surgery patients tell me, as well as experiencing the same thing myself.
We go to bed at about 11 p.m. and at about 2-3 a.m. we are awakened by pain.
I have, on more than one occasion, been awakened by low back disc problems at 2-3 in the morning with pretty severe pain. I have sat at my kitchen table wringing my hands trying not to “give in” to taking more pain medication, and at sunrise, I get a significant reduction in pain. Enough relief that I can go back to bed and sleep till about 10 a.m. Upon awakening, my pain levels are tolerable even without pain medication.
My experience has always been in regard to lumbar flare-ups from having considerable joint and disc degeneration, not a surgical procedure, so I had not been taking prescription pain medications before the lumbar flare-up. I really try to avoid them if I can.
But my experience translates perfectly to the physiology of endorphins and enkephalins, as well as matching the pattern of my patient’s symptoms of pain after total knee surgery.
So I took this information and experience and came up with my own intervention philosophy to break that 2-3 a.m. pain increase.
Tip 3: Take Your Last Pain Medication at Midnight or Later.
I suggest to my patients who are experiencing total knee surgery pain increase in the middle of the night, to put off that last dose of pain medications until midnight or after.
The pain medications usually have an effective time frame from 4 to 6 hours after taking the medication. Delaying the last pain medication intake until after midnight should carry the patient through that 3-4 hour window of decreased or absent endorphins and enkephalins.
All the total knee surgery patients, who have followed this advice of taking the last medications at midnight or later, have reported they were able to sleep through the night without pain waking them.
One thing to keep in mind is that the patients I am discussing here are new total knee surgery recipients.
Almost 100% of these patients were taking opioids prior to total knee surgery, so they already had a tolerance to opioids, making the prescribed pain medications less effective.
These are patients that are no more than 3-4 weeks out from their surgery date.
Night pain can be a sign of more sinister pathology and if severe or prolonged pain persists after total knee surgery, it needs to be evaluated by the surgeon.
A study, Circadian Rhythms, Sleep, and Substance Abuse, states substance abuse can cause a disturbance in the circadian release of endorphins and enkephalins making the patient even more vulnerable to night pain.
While the new total knee recipients taking opioids after their surgery certainly are not substance abusers, they are in fact taking the drugs that are most commonly abused.
It makes sense to me that the pain medications prescribed are both suppressing the patient’s body to produce its own painkillers and its own anti-inflammatories.
They can interfere with sleep just by themselves.
Sadly, many of my patients were taking opioids prior to the total knee surgery to control their pain and improve mobility. Some had been taking it for months.
See my article: Knee Pain After Total Knee Surgery: A Physical Therapist’s View
Tip 4: Use Good Sleeping Postures.
After a total knee surgery, all my patients sleep on their back, or on one side or the other. I have never seen a total knee replacement patient that could sleep on their stomach, at least not initially.
Each of these three positions has the potential to increase the patient’s knee pain at night but for different reasons with different intervention solutions.
Sleeping On Your Back:
Most of my total knee surgery replacement recipients are sleeping on their back, at least for the first few days after surgery.
The patients who are having trouble with that position (because of breathing or other issues) usually tell me they are sleeping in their recliner chair.
See my article: Can I Sit In A Recliner After Knee Replacement? A PT’s Advice
Sleeping in a recliner chair is a great solution for a few days, but after a while, even with the recliner chair tilted back all the way, the amount of weight that is put on the tailbone (coccyx) becomes uncomfortable and most of my patients transition back into bed with a side-lying posture.
Sleeping on the back puts the operated leg into full available extension and many patients without full extension range of motion find this position generates too much pain in the knee.
This is because the knee will not come out straight allowing the back of the knee to be supported by the bed.
It’s kind of like leaning on the wall with the hand in extension, initially it feels fine but after a while the wrist begins to complain because of the stretching that is happening to the wrist in this position.
Frequently my patients are using a pillow under their knee to support the knee to get rid of that stretching pain.
I discourage the use of a pillow under the knee in bed or in the recliner chair. While this position is comfortable for the patient, it is counterproductive to gaining a full extension range of motion.
The extension range of motion has a window of about 6-8 weeks for achieving a full extension range of motion. After that time frame, it becomes much more difficult to get to full knee extension.
At this 6-8 weeks post-op stage of rehabilitation, and not achieving the standard of 10 degrees short of extension or less, the surgeon will be thinking of manual manipulation of the knee. They will be considering taking the patient back to the operating room and, under anesthesia, manually manipulating the knee to break up the scar tissue that is forming.
See my article: Total Knee Replacement Manipulation: (When & Why To Consider)
My patients are encouraged to sleep on their back without a pillow under their knee, and if that position becomes uncomfortable, switch to a side-lying position instead of stuffing a pillow under the knee.
Sleeping Side-Lying On The Unoperated Side:
This seems to be the most comfortable for my total knee surgery patients if they are properly supporting the operated leg.
Most patients have heard that putting a pillow between their legs when sleeping side-lying is the correct way to sleep on the unoperated side, and they would be correct.
Most of my total knee surgery patients are using the wrong pillow size between their legs the first time I see them.
They are sleeping on the unoperated side with a REGULAR-SIZED PILLOW between their knees.
They need to sleep with a Body Pillow (Amazon link).
Since the pillow does not support the foot and ankle (and sometimes up to mid-calf), the pillow creates a fulcrum over the knee, and the foot/ankle weight is trying to bend the knee sideways.
The correct way to sleep on the unoperated side is to use a body pillow (like a pregnancy pillow). The bottom of the pillow should extend past the foot and ankle as the patient rests their leg on the pillow.
This pillow support needs to extend up the leg to the groin area at the hip. Most body pillows will extend up further than the groin.
This technique of full support of the operated leg completely eliminates any lateral stress on the knee.
My patients often modify this position by placing the body pillow slightly in front of the bottom leg, then slightly flexing at the hip, and resting the operated leg on the pillow fully supported.
These pillows will separate during the night and place the knee in a stressed position.
If a body pillow is not an option, the patient can use multiple regular pillows to achieve the same positioning, but the pillows tend to separate over time.
Wrapping the pillows in a sheet and binding them into a solid unit is advisable.
Sleeping Side-Lying On The Operated Side:
The biggest problem my total knee surgery patients have sleeping on the operated knee side is usually the “contact pain” from the mattress or from the unoperated leg.
The outside of the knee can be sore and sensitive enough that even its own weight against the mattress causes increased pain. Relieving the weight on the knee can be reduced by using a body pillow to prop up the unoperated leg positioned in front of the operated leg.
The other, more common complaint I hear from my total knee surgery patients is that when they are sleeping side-lying with the operated leg down, the top leg knee rests on the operated knee and causes pain.
Again, using a body pillow to position the top leg forward so the knees do not touch is the best solution.
Read my other articles about Total Knee Replacement
Wishing You A Restful Full Night’s Sleep
Paying It Forward
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