What should you know about causes of muscle cramps at night?

A calf, foot, or thigh muscle may contract suddenly and stay tight for a short time. Long periods of standing, unfamiliar exercise, a [Muscle Strain](/conditions/muscle-strain/), or reduced flexibility can make cramping more likely. Fluid loss from heat, sweating, vomiting, or diarrhoea may contribute, as can changes in minerals or medicines. Night cramps can also occur alongside [Dehydration](/conditions/dehydration/), [Peripheral Arterial Disease](/conditions/peripheral-arterial-disease/), or nerve and muscle changes.

Recurring cramps do not point to one diagnosis. [Chronic Kidney Disease](/conditions/chronic-kidney-disease/), [Hypothyroidism](/conditions/hypothyroidism/), low vitamin D, and loss of muscle mass can affect muscle function, but symptoms and examination are needed to judge whether they are relevant.

When a cramp starts, stop the activity, gently stretch the affected muscle, and massage it if this is comfortable. Afterward, note its location, time, duration, triggers, recent exercise, fluid losses, and medicines. Regular movement, gradual training, comfortable footwear, and adequate fluids may reduce triggers. Avoid starting mineral or vitamin supplements without advice; the right treatment depends on the cause. A clinician can review recurrent [Muscle Cramps](/symptoms/muscle-cramps/) and decide whether tests or medication review are useful.

Arrange a clinical review if cramps are frequent, disturb sleep repeatedly, last longer than expected, or come with weakness, numbness, swelling, skin colour change, or reduced walking ability. Seek urgent care for severe persistent pain, a cold or pale limb, sudden swelling, or weakness that begins abruptly. Contact a clinician sooner if cramps follow major fluid loss or occur with known kidney, thyroid, or circulation problems.

Could my medicines, hydration, circulation, thyroid, kidney function, or vitamin levels contribute? Do I need blood tests? Which stretches are suitable? What symptoms should make me seek urgent help?