What could be causing my restless leg symptoms that improve when laying flat?

Restless Legs Syndrome (RLS) is the Most Likely Diagnosis

Your symptoms—leg restlessness while sitting that improves when laying flat—strongly suggest Restless Legs Syndrome (RLS), a sensorimotor disorder characterized by an urge to move the legs that worsens with inactivity and follows a circadian pattern. 1

Diagnostic Criteria to Confirm RLS

You need to meet all five essential criteria to confirm RLS 1:

• An urge to move the legs usually accompanied by uncomfortable or unpleasant sensations (described as creepy-crawly, burning, itching, or restless feelings) 1
• Symptoms begin or worsen during rest or inactivity such as sitting or lying down—this matches your sitting symptoms 1
• Symptoms are partially or totally relieved by movement such as walking or stretching, at least as long as the activity continues 1
• Symptoms occur or worsen in the evening or night compared to daytime 1
• Symptoms are not better explained by another condition like leg cramps, venous stasis, leg edema, arthritis, or positional discomfort 1

Why Your Symptoms Improve When Laying Flat

The improvement when laying flat is somewhat atypical for classic RLS, which typically worsens with any rest or inactivity regardless of position 1. However, this could represent:

• Positional relief if you're unconsciously moving more when lying down 1
• A mimic condition such as venous stasis or positional discomfort that superficially meets RLS criteria 1, 2
• Early or mild RLS with incomplete symptom expression 1

Critical Questions to Differentiate RLS from Mimics

Ask yourself these specific questions 2, 3:

• "What does it feel like?" RLS = urge to move with dysesthesias; leg cramps = painful tightening 2
• "Is it relieved by movement?" RLS = relieved by any movement but returns when stopped; cramps = relieved specifically by stretching the muscle 2
• "When does it occur?" RLS = worse in evening/night; cramps = typically nocturnal but no circadian pattern 2, 3

Essential Initial Workup

Before any treatment, you must address potential secondary causes 1, 4:

1. Check serum ferritin and transferrin saturation (morning fasting, after avoiding iron supplements for 24 hours)—iron deficiency is a major treatable cause 1, 4
2. Review all medications for RLS-exacerbating agents: tricyclic antidepressants, SSRIs, lithium, antipsychotics (dopamine antagonists), antihistamines 1, 2
3. Screen for associated conditions: renal disease, peripheral neuropathy, pregnancy, anemia 1, 5
4. Assess for sleep apnea using questionnaires like STOP-BANG if you have daytime sleepiness 1

Treatment Algorithm

First-Line: Iron Supplementation (if deficient)

If ferritin ≤75 ng/mL or transferrin saturation <20%, start iron supplementation immediately—this threshold is higher than general population guidelines because brain iron deficiency drives RLS pathophysiology 1, 4:

• Oral ferrous sulfate (conditional recommendation, moderate certainty) 1, 4
• IV ferric carboxymaltose (strong recommendation, moderate certainty) if oral fails or for faster response 1, 4

First-Line Pharmacological Treatment

Alpha-2-delta ligands are now first-line therapy (strong recommendation, moderate certainty) 1, 4:

• Gabapentin 300-2400 mg/day divided three times daily 1, 4
• Gabapentin enacarbil (prodrug with better bioavailability) 1, 4
• Pregabalin (allows twice-daily dosing) 1, 4

These agents avoid the augmentation phenomenon (paradoxical worsening) seen with dopamine agonists 1, 6.

Medications to AVOID

Dopamine agonists (pramipexole, ropinirole, rotigotine) are now recommended AGAINST for standard use due to high risk of augmentation—a progressive worsening characterized by earlier symptom onset, increased severity, and anatomic spread 1, 7. They may only be considered short-term if you prioritize immediate symptom relief over long-term adverse effects 1.

Specifically avoid 1, 4:

• Levodopa (conditional recommendation against, very low certainty—high augmentation risk) 1
• Cabergoline (strong recommendation against) 1
• Clonazepam (conditional recommendation against—insufficient efficacy evidence) 1, 4

Common Pitfalls to Avoid

• Don't assume electrolyte depletion causes your symptoms—this theory is poorly supported for RLS 2
• Don't confuse RLS with nocturnal leg cramps—cramps are painful muscle contractions relieved by stretching, not general movement 2, 3
• Don't ignore medication review—many common drugs worsen RLS including antidepressants and antihistamines 1, 2
• Don't use dopamine agonists as first-line—despite FDA approval, current guidelines prioritize alpha-2-delta ligands due to augmentation concerns 1, 7

When to Seek Further Evaluation

Consider polysomnography if 1, 3:

• Diagnosis remains unclear after clinical evaluation
• Suspected periodic limb movement disorder (PLMD) with sleep disruption not explained by RLS alone
• Suspected coexisting sleep apnea

Up to 90% of RLS patients have periodic limb movements during sleep, but these are not required for RLS diagnosis 1, 3.