Nocturnal pruritus is the medical term for itching that intensifies or only appears at night. This common sensation frequently affects the ankles and feet, often becoming intense enough to disrupt sleep, leading to fatigue. While the urge to scratch can be significant, most causes relate to skin irritation or minor conditions. Understanding the reasons behind this nightly phenomenon is the first step toward finding relief and restoring restful sleep.
Common Topical Irritations and Dryness
The skin around the ankles is particularly susceptible to everyday, non-infectious irritations that cause itching. Xerosis, or dry skin, is a frequent culprit, often becoming more noticeable when the body is at rest. Low humidity environments, especially those created by indoor heating systems during colder months, strip moisture from the skin, weakening its natural barrier function. This loss of moisture can lead to scaling, slight cracking, and the sensation of itchiness.
Contact dermatitis presents another common cause, resulting from the skin reacting to a substance it encounters. This reaction can be an allergic response to an ingredient in a new laundry detergent, a fragrance in a lotion, or the dyes used in socks or shoes. Alternatively, it may be an irritant reaction caused by friction from rough sock material or the tight elastic of hosiery rubbing against the skin. Identifying and removing the offending material usually resolves the irritation and the nocturnal itching.
Fungal Infections and External Pests
Causes involving living organisms, such as fungal infections or external pests, often explain why ankle itching is persistent and intense. Tinea pedis, commonly known as Athlete’s Foot, is a fungal infection that thrives in the warm, moist environment created by socks and bedding. The infection typically manifests as intense itching, often accompanied by redness, peeling, or scaling of the skin, and can spread from the toes to the soles and ankles. This fungal growth is frequently mistaken for dry skin, delaying the application of appropriate antifungal treatment.
External pests that are primarily active at night can also target the ankles, causing sudden, localized itching. Bed bugs, for example, typically feed while a person is asleep, and their bites often appear on exposed skin like the lower legs and ankles. Similarly, fleas from pets may jump onto the ankles and lower legs, leading to clusters of itchy, red welts. Scabies, caused by microscopic mites that burrow into the skin, is notorious for causing an extremely intense itch that characteristically worsens after dark.
The Biological Reason Itching Worsens at Night
The body’s internal clock, or circadian rhythm, intensifies the sensation of pruritus after sunset. As the body prepares for sleep, there is a natural rise in skin temperature and increased blood flow to the skin’s surface. This slight increase in heat and circulation enhances the activity of nerve endings, making the skin more sensitive to minor irritations.
Hormonal changes following the circadian cycle also contribute to increased sensitivity. The body’s production of anti-inflammatory hormones, such as cortisol, naturally dips to its lowest point between midnight and early morning. This reduction removes a natural suppression mechanism against inflammation, allowing existing irritation to feel more pronounced. Simultaneously, the body may release higher levels of pro-inflammatory substances, like certain cytokines, which further trigger the itch sensation. The lack of distractions in a quiet, dark room also shifts focus inward, increasing awareness of minor sensations.
When Ankle Itching Signals a Systemic Issue
While many causes relate to the skin’s surface, persistent, widespread itching can occasionally indicate an underlying systemic medical condition. Disorders affecting the liver, such as cholestasis, can cause widespread pruritus. This is thought to be related to the buildup of certain compounds, like bilirubin, in the bloodstream. Chronic kidney disease can also lead to generalized itching, a condition termed uremic pruritus, which is often more troublesome at night.
Endocrine issues, including diabetes and thyroid disorders, are other possible systemic contributors. Uncontrolled diabetes can cause peripheral neuropathy, where nerve damage in the extremities can manifest as abnormal sensations, including persistent itching or tingling in the feet and ankles. Itching that is bilateral, affects large areas of the body, is not relieved by moisturizing, or is accompanied by other symptoms requires medical attention. Unexplained fatigue, significant weight changes, or jaundice serve as red flags indicating a need for professional medical evaluation to determine the true source of the nocturnal itch.