What usually causes itEmerging evidence
Ankle pain is common: 11.7% of UK adults aged 50 and over had it in the past month, and 3.4% had painful ankle arthritis on X-ray. Most ankle arthritis follows an injury: at one specialist centre, 78% of 406 painful, worn ankles followed an injury, and only 9% were wear and tear with no other cause. After a sprain, 5% to 33% of people still had some pain a year later. The NHS lists a sprain, Achilles tendonitis, bursitis and a break among the causes of ankle pain.
At night the list widens: gout, which most often flares overnight; a squeezed nerve; cramps and restless legs; poor circulation; swelling that gathers by the evening; and, rarely, a stress fracture, an infection or a bone tumour.
Sources 1, 2, 3, 4
Why the ankle can hurt more in bed: what's known and what's borrowedEmerging evidence
Arthritis (borrowed evidence): the NHS lists more pain and stiffness after you haven't moved a joint for a while among osteoarthritis symptoms, and says that in more severe cases symptoms can be continuous. The night pain figures come from hips and knees: in focus groups, 81% of 123 people with hip or knee osteoarthritis had night pain, at every stage and varying from night to night. No study we found measured night pain in ankle arthritis.
Gout (known): in 724 people followed for a year, attacks were 2.36 times more likely between midnight and 8am than in the daytime, even without alcohol or rich food, and Arthritis UK says even the weight of a bedsheet can be unbearable. Nerves: one review says tarsal tunnel pain is typically worse at night, though that rests on a single author's review; peripheral neuropathy, which affects almost 1 in 10 people aged 55 and over, brings burning, stabbing or shooting pain in the feet. Circulation: when the blood supply to the leg is badly reduced, a severe burning pain carries on even at rest.
Cramps and restless legs come at rest: the NHS says leg cramps mostly happen at night or when resting and can affect the feet, and restless legs are usually worse at night. Swelling gathers in the lowest parts of the body through the day, the NHS explains for pregnancy. A stress fracture starts as pain with activity and can become a constant dull ache, even at night, and a rare benign bone tumour, osteoid osteoma, caused night pain in 69% of 223 reported foot and ankle cases.
Sources 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17
Pain, sleep and the body clockEmerging evidence
Sleep and pain affect each other: in studies that follow people over time, sleep problems predict new and worse long-lasting pain more strongly than pain predicts poor sleep, a review found. In a laboratory study of healthy volunteers kept awake under controlled conditions, pain sensitivity was highest in the middle of the night and lowest in the afternoon. That study wasn't in people with pain, so applying it to ankle pain at night is our inference. The NHS's sleep habits, and talking therapy for insomnia that lasts, are the tools for the sleep side.
Sources 18, 19, 20
When night pain needs checkingStrong evidence
The reassuring pattern, in our reading of the sources: pain that eases when you move or change position, is linked to what you did that day, and comes and goes from night to night. The company that needs checking: a hot, swollen joint with a fever; a swollen, throbbing calf, or one swollen ankle with no known cause; bone pain that is constant or worse at night, with a lump, swelling or weight loss; a burning foot at rest with pale or cold toes; a hot, swollen foot if you have diabetes; and pain in one spot on a bone that started with activity.
On its own, night pain is a weak sign: at a back pain clinic, 213 of 482 people had night pain, 90 of them every night, and none was found to have a serious disease. That study was in back pain, not ankle pain.
Sources 21, 22, 23, 24, 25, 11, 26, 16, 27
Tests and scansEmerging evidence
NICE diagnoses osteoarthritis from the symptoms without a scan in people aged 45 or over, and X-ray changes in the ankle often don't match the symptoms: in a laboratory study, symptoms went with weaker muscles, less movement and more disability rather than with the X-ray. Gout is confirmed with a blood test for urate, or fluid from the joint if that is unclear. A suspected clot needs an ultrasound scan, and narrowed arteries are checked by comparing the blood pressure at the ankle and the arm. Osteoid osteoma shows best on computed tomography (CT): magnetic resonance imaging (MRI) missed a third of cases. A suspected Charcot foot is X-rayed standing, with an MRI if the X-ray is normal but the worry remains.
Sources 28, 29, 30, 23, 11, 17, 26
How it usually goesEmerging evidence
After a sprain, pain eases quickly in the first 2 weeks, but 5% to 33% of people still have some pain at a year, and 36% to 85% report a full recovery within 3 years. Osteoarthritis symptoms come and go, and night pain in hip and knee arthritis varies from night to night. An untreated gout attack usually lasts 1 to 2 weeks, and medicine taken as soon as it starts should begin to work within 2 days. Nightly stretching reduced cramps over 6 weeks in a trial. No one can promise a timescale.
Sources 3, 5, 6, 31, 32