Night splints are a common thing that are recommended for treatment of plantar fasciitis or plantar fasciosis (PF). A night splint is a device that is worn while a person sleeps to keep their foot held up in a position like you were walking on your heels. This position is called dorsiflexion and it stretches the calf and Achilles tendon at night. They are commonly recommended by physicians, physical therapists, chiropractic physicians and even podiatrists. But just because it is a popular or common treatment for heel pain does not mean that it is actually effective^1,2. Some organizations have guidelines that recommend night splints to treat plantar fasciitis or Achilles tendonitis. It is true that night splints have been shown to decrease pain in the short term and placate a patient, but that does not mean that it helps long term. Biomechanically, it does not make sense.

There are a couple of problems with stretching the plantar fascia. The main reason is that stretching the plantar fascia is why someone has pain is that the plantar fascia in the first place. Every time that you step, your foot actually lengthens from heel to toe while your arch drops and that imparts stress to the plantar fascia.

PF is the result of the plantar fascia being stretched too much or being overloaded over time, so PF is like a sprain since the plantar fascia is basically a ligament. You should not do stretches of a muscle or joint after someone strains a muscle or sprains a joint. After the injury, you need to protect and stabilize the area for a period of time until it starts to heal. Again, PF is an accumulation of trauma and repeated overloading/overstretching of the plantar fascia. Accumulated overloading is the same basic mechanism that causes tendonitis/tendonosis too.

A night splint makes the symptoms feel better in the morning after wearing it all night, because the plantar fascia is already stretched before your foot hits the ground first thing in the morning. That means the injury does not re-rip open when you step on it because it has been held open all night. So that means that it can be effective at reducing the pain that people feel first thing in the morning, but it doesn’t actually help to heal the problem that is causing the heel pain.

If you had a nasty horizontal cut on the back of your elbow and kept your arm straight, you would start to approximate the tissues and it would heal. But every time that you bent your elbow while it was healing, you would feel pain from the cut ripping apart. If you bent your elbow enough then eventually it wouldn’t hurt at the cut anymore. The same thing happens with plantar fasciitis when someone is non-weightbearing for a period of time and then becomes weightbearing.

The pain is there while they stretch the plantar fascia out and then once it’s been really ripped back open it no longer hurts. Sit for too long and it starts to heal, but once you stand, it hurts. It hurts most in the morning since you have spent so much time non-weightbearing as you sleep.

The equivalent of a night splint would be sleeping with your arm bent all night long and splinted with your hand next to your shoulder in order to keep that elbow cut open. It would prevent it from hurting when you straighten out the elbow and then re-bend it again. The problem is that although it won’t hurt when you bend the elbow again, it is not going to heal right since edges are not going to be close enough to mend the break.

Mostly,  I have found the only thing that a night splint is good for is to annoy the person wearing it. People just do not sleep well with them on. The studies that I have looked at seem to show that night splints relieve pain in the short term but not long term. There are no differences between giving a patient home exercises or home exercises with a night splint¹. No real difference at 6 weeks or 3 months. Other studies show a night splint might help compared to no other treatment after wearing it for 8 weeks but there was no difference after wearing it for 2-2.5 years. Night splints also have the ability to damage your sheets as well.

FYI, not stretching the plantar fascia includes not doing stretches to the affected foot itself. Not with your hand and not with your foot up a wall. A typical runner’s stretch against a wall with a supported back foot with a straight back leg (gastrocnemius m.) and with a bent back leg (soleus m.) are the ways to go.

So people with plantar fasciitis should be treated with manual therapy by chiropractor or PT that knows what they are doing. The exercises that a person should be doing are more than just scrunching a towel with your toes. Stretches and custom-made foot orthotics are effective tools to prevent excessive loading of the plantar fascia but the exercises are the main thing to make it go away. 

1. Wheeler PC. The addition of a tension night splint to a structured home rehabilitation programme in patients with chronic plantar fasciitis does not lead to significant additional benefits in either pain, function or flexibility: a single-blinded randomised controlled trial. BMJ Open Sport Exerc Med. 2017 Jun 13;3(1):e000234. doi: 10.1136/bmjsem-2017-000234. eCollection 2017. 
2. Sussmilch-Leitch SP, Collins NJ, Bialocerkowski AE, Warden SJ, Crossley KM. Physical therapies for Achilles tendinopathy: systematic review and meta-analysis. J Foot Ankle Res. 2012 Jul 2;5(1):15. doi: 10.1186/1757-1146-5-15.