While highly improbable, it is physically possible to sprain an ankle during sleep. A sprain is a traumatic injury where the ligaments—the tough, fibrous tissues connecting bones—are stretched or torn by a sudden, forceful movement beyond their normal range of motion. Since the body is typically at rest and not bearing weight during sleep, the necessary force to damage these ligaments is usually absent. However, certain scenarios involving external forces or involuntary internal movements can create the conditions for a true sprain to occur while unconscious.
Understanding the Ankle Injury Mechanism During Sleep
A true sprain requires an acute, excessive force that wrenches the ankle joint, most commonly causing an inversion injury where the foot rolls inward. While sleeping, this can happen if the foot becomes entangled in a heavy comforter or bedding, which then acts as a lever to twist the joint abnormally as the body shifts position. If the foot is forcefully trapped in an awkward, inverted position and a sudden body movement occurs, the ligaments can be stressed past their breaking point.
A more severe, external mechanism involves the individual falling out of bed, where the foot is caught or lands awkwardly on the floor or a nearby object. Even without falling, an uncontrolled, forceful rotation of the ankle can be induced by a severe, acute nocturnal muscle spasm, such as a charley horse. These involuntary muscular contractions, though rare in their severity, can be powerful enough to yank the foot into a position that overstretches the surrounding ligaments.
Common Causes of Waking Up with Ankle Pain That Aren’t Sprains
The majority of people who wake with acute ankle pain have not suffered a sprain but are experiencing symptoms from other conditions exacerbated by long periods of rest.
Plantar Fasciitis
One common cause is plantar fasciitis, which involves inflammation of the thick band of tissue running along the bottom of the foot. During sleep, the foot often rests in a pointed position, which allows the plantar fascia to shorten. The first steps in the morning then cause a sharp, tearing pain as the tissue is suddenly stretched.
Tendinitis and Arthritis
Another frequent cause is tendinitis, the inflammation of a tendon, such as the Achilles tendon. Tendons stiffen during inactivity, meaning the first movements after waking can be painful until the tissue warms up. Inflammatory arthritis, including rheumatoid arthritis and gout, is also characterized by morning stiffness and pain. Gout involves a buildup of uric acid crystals in a joint, often the big toe, but it can affect the ankle, causing sharp pain, warmth, and swelling that often flares up overnight.
Positional Stress and Nerve Compression
The way a person sleeps can also contribute to discomfort, known as positional stress. Sleeping with the foot in a pointed position for hours can shorten the calf muscles and Achilles tendon, leading to morning stiffness. Furthermore, compression of nerves, such as in Tarsal Tunnel Syndrome, can cause a burning sensation or numbness in the foot and ankle area that becomes more noticeable after a period of immobility. Unlike a sprain, which typically presents with immediate, noticeable swelling and bruising at the moment of injury, these conditions usually feature pain that gradually improves with movement.
Immediate Care and When to Seek Professional Help
For a sudden onset of ankle pain, regardless of the cause, initial management should focus on the R.I.C.E. protocol: Rest, Ice, Compression, and Elevation. Rest by keeping weight off the ankle. Apply ice wrapped in a thin towel for 15 to 20 minutes several times a day to reduce inflammation. Use a compression bandage to control swelling, and elevate the ankle above the level of the heart to encourage fluid drainage.
While minor causes of morning pain resolve with home care, certain “red flag” symptoms require immediate medical evaluation. Seek professional help if you experience severe, unrelenting pain or are completely unable to bear weight on the foot. Urgent signs include a visible deformity, a snapping or grinding sound heard when the pain started, or signs of infection such as fever, increasing warmth, or redness. If pain and swelling do not improve after two to five days of at-home care, a consultation is necessary to rule out a moderate sprain or a fracture.