Leg Pain at Night: What's Causing It, and What an Ultrasound Shows

Leg pain at night is one of those complaints that gets waved off because it is so common. Up to 60 percent of adults report having had nocturnal leg cramps (American Family Physician, 2012), and most of the time that is exactly what is happening. But buried in that same complaint is a presentation called ischemic rest pain, which means the arteries feeding the foot can no longer supply it even at rest. Those two things are confused constantly, and the stakes are not symmetrical: one resolves with a stretch, the other is the stage of peripheral artery disease that vascular specialists treat as urgent. This article explains how to tell them apart, what the other causes look like, and what an ultrasound actually settles.

The Short List of Things That Cause Leg Pain at Night

Night-time leg pain has a genuinely short differential. In order of how often it turns up in practice: nocturnal leg cramps, restless legs syndrome, peripheral neuropathy, lumbar spinal stenosis, venous insufficiency, and arterial rest pain. The first five are uncomfortable. The last one means tissue is ischemic.

What makes this sortable is that each cause has a signature made up of three things: where the pain sits, what it feels like, and what makes it stop. Patients almost always know all three and are rarely asked. A cramp is in the calf, feels like a vise, and stops when you pull your toes toward your shin. Rest pain is in the ball of the foot and the toes, feels like burning or deep aching, and stops when the leg goes below the level of the heart. Those are not variations on one symptom. They are different diseases that happen to share a time of day.

Ischemic Rest Pain: Why Narrowed Arteries Hurt Most When You Lie Down

In a healthy leg, the arteries carry far more capacity than the tissue needs, so position and sleeping blood pressure are irrelevant. In a leg with significant peripheral artery disease, that reserve is gone. The arterioles downstream of the blockage are already dilated as far as they will go, which means blood flow to the foot is no longer regulated by the foot — it is dictated by the pressure arriving from above.

Two things happen when you go to bed. Systemic blood pressure drops during sleep, and lying flat removes the column of gravity that was helping push blood into the foot. A study that recorded 24-hour blood pressure alongside forefoot blood flow in patients across a range of arterial disease severity found mean arterial pressure fell an average of about 19 percent from waking to sleep, regardless of symptoms. What differed was the consequence: forefoot blood flow fell 32 percent in the limbs with ischemic nocturnal rest pain, against 16 percent in limbs that had arterial insufficiency but no rest pain (Scand J Clin Lab Invest, 1987). The authors concluded that nocturnal hypotension is the major factor producing the symptom.

That mechanism explains the behaviour patients describe without being prompted. They hang the foot off the mattress. They sleep sitting in a recliner. They get up and walk around the bedroom, which both stands the leg up and raises blood pressure. Each of those restores perfusion pressure, and the pain recedes within minutes. Patients who have been doing this for months often do not mention it, because they have reclassified it as a sleep habit rather than a symptom.

Night Cramps Are Not Rest Pain: How to Tell Them Apart

Up to 60 percent of adults report having had nocturnal leg cramps (American Family Physician, 2012). They are so prevalent that they become the default explanation for any night-time leg symptom, which is precisely the problem. Four features separate them:

Onset. A cramp arrives in a second, at full intensity. Rest pain builds over many minutes and is often what wakes you rather than something you wake into.

Duration. Cramps last from several seconds to a few minutes and then stop completely. Rest pain persists for as long as the leg stays horizontal, which can be hours.

What relieves it. Stretching the calf aborts a cramp. Stretching does nothing for rest pain; changing the height of the limb is what works.

Location. Cramps are muscular — calf, hamstring, arch. Rest pain is in the forefoot and toes, where perfusion pressure is lowest and the tissue is furthest from the heart. A patient pointing at their toes is describing a circulatory problem, not a muscle one.

The confusion runs in both directions, which is worth saying plainly: most people with night cramps have no arterial disease at all, and telling them otherwise is its own harm. The point is not that cramps are sinister. It is that "probably cramps" is a conclusion, not a starting position, and the forefoot pattern deserves a different one.

The Other Causes Worth Naming

Restless legs syndrome

Restless legs is not primarily painful. It is an urge to move, usually described as crawling or electrical, that is relieved by movement and returns within seconds of stopping. The distinguishing question is whether movement relieves it or whether position does. Rest pain patients want the leg down; restless legs patients want it moving.

Peripheral neuropathy

Diabetic and other peripheral neuropathies produce burning, tingling and numbness in a stocking distribution across both feet, worse at night when there is less sensory distraction. The overlap with rest pain is real and it is clinically treacherous, because neuropathy and arterial disease share diabetes as a risk factor and frequently coexist in the same foot. Neuropathy also blunts the pain of ischemia, which is why a diabetic patient can reach an advanced stage of arterial disease with surprisingly mild symptoms. In this group the symptom history alone cannot settle the question; that is what pressure measurements are for.

Lumbar spinal stenosis

Spinal stenosis causes neurogenic claudication, which mimics vascular claudication closely enough that the two are routinely mistaken for each other. The classic discriminator is that stenosis improves with spinal flexion — leaning on a shopping cart, sitting forward — while vascular claudication improves simply with standing still. Stenosis is also independently associated with night cramps: in a community study of 328 volunteers who each had a lumbar MRI, 65.2 percent reported nocturnal leg cramps, and the narrowest dural sac cross-sectional area was statistically related to their presence (Int J Gen Med, 2022).

Venous disease and clot

Venous insufficiency produces heaviness and aching that is worst after a day on your feet and better with elevation — the exact inverse of arterial rest pain. Deep vein thrombosis produces a more constant unilateral ache with swelling, warmth and calf tenderness that does not particularly care what time it is. If the leg is swollen as well as painful, that changes which study is indicated; our guide to what causes leg swelling covers that branch.

What an Arterial Duplex Ultrasound Actually Measures

The 2024 ACC/AHA peripheral artery disease guideline makes the ankle-brachial index the diagnostic test for anyone with findings suggestive of PAD, with the toe-brachial index substituted when the ankle arteries are non-compressible (Circulation, 2024). That index gives you a number for the whole limb. A lower extremity arterial duplex is what tells you where the problem is, which is the information that determines whether anything can be done about it.

Ankle-brachial index. Ankle systolic pressure divided by the higher brachial pressure. Values below 0.90 are diagnostic of PAD; values below roughly 0.40 are the range in which rest pain and tissue loss appear. Heavily calcified vessels, common in diabetes and chronic kidney disease, resist compression and can return a falsely normal or even elevated index, which is why toe pressures exist (Circulation, 2012).

Segmental pressures and waveforms. Pressures taken at thigh, calf and ankle localize the drop to a level. The Doppler waveform shape tells you the rest: a healthy artery at rest is triphasic, a diseased one loses its reverse-flow component and becomes biphasic, then monophasic and blunted downstream of a significant obstruction.

Peak systolic velocity and velocity ratio. Blood accelerates through a narrowing. Measuring peak systolic velocity inside the lesion and comparing it to the normal segment just upstream grades the stenosis. The ratio matters more than the raw number, because it is internally referenced to that patient's own circulation.

Direct imaging of plaque and occlusion. B-mode and colour Doppler show plaque burden, where flow stops entirely, and whether collateral vessels have formed around an occlusion. A 2025 systematic review of 15 studies covering 9,067 arteries found pooled sensitivity of 0.86 and specificity of 0.95 against arteriography in symptomatic patients, with the femoropopliteal segment performing best and below-the-knee arteries weakest at 0.78 sensitivity (J Vasc Bras, 2025). That below-knee limitation is worth knowing: it is the segment most often involved in diabetic disease, and it is the reason a negative duplex in a high-risk diabetic foot is not the end of the workup.

No radiation, no contrast, no needle. For a patient whose kidneys rule out CT angiography contrast, that is not a convenience — it is the only non-invasive map available.

What Changes If You Wait

Peripheral artery disease is common and quiet. In NHANES data, 4.3 percent of American adults over 40 had an ankle-brachial index below 0.90, which worked out to roughly 5 million people (Circulation, 2004). The disease does not announce itself at onset; it announces itself at a stage.

A meta-analysis of progression in peripheral arterial disease found that the limb risk had been underestimated: around 7 percent of asymptomatic patients progressed to intermittent claudication, roughly 21 percent of claudicants were later diagnosed with critical limb ischemia, and between 4 and 27 percent of those underwent amputation. Five-year cardiovascular mortality in symptomatic PAD was 13 percent against 5 percent in the reference population (Eur J Vasc Endovasc Surg, 2016). A pooled analysis of patients with severe or critical limb ischemia who went untreated reported all-cause mortality of about 22 percent and major amputation of about 22 percent at a median of twelve months (J Vasc Surg, 2015).

Rest pain is the symptom that marks the transition between those two sets of numbers. It is also, read correctly, a warning that typically comes before tissue loss rather than after it. The broader point is that the same arterial disease is rarely confined to the leg, which is why finding it changes how aggressively the whole cardiovascular risk profile gets managed. If your pain comes on when you walk rather than when you lie down, start with our article on claudication; if your legs feel cold, heavy or discoloured, poor circulation in the legs covers the broader picture.

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