Evaluating Erectile Health During Sleep

When addressing erectile dysfunction (ED – 발기부전), it’s essential to determine whether the issue is physical or psychological. One of the most reliable, non-invasive ways to make this distinction is through the Nocturnal Penile Tumescence (NPT) test (야간 발기 검사 – yagan balgi geomsa). At specialty clinics like Gangnam J Urology Clinic, this diagnostic test is used to monitor nighttime erections and gain insight into the underlying causes of ED—so that treatment can be more accurate and effective.

What Is the NPT Test?

The NPT test is a sleep-based erectile function study that monitors whether spontaneous erections occur during the night. Healthy men typically experience 3 to 5 erections during sleep, particularly during REM (rapid eye movement) cycles. If nighttime erections are present, it suggests that the erectile dysfunction may have a psychological or stress-related origin. If they are absent, a physical issue such as poor blood flow, nerve damage, or hormonal imbalance may be to blame.

Who Should Consider an NPT Test?

Your doctor may recommend an NPT test if you:

• Have ongoing erectile dysfunction with no clear cause
• Show normal hormone levels but still experience ED
• Want to determine whether your ED is organic or psychogenic
• Have tried medications (like Viagra) without success
• Are evaluating options for penile implant surgery or other advanced treatment

The NPT test is particularly useful when standard exams and blood tests are inconclusive.

How Is the NPT Test Performed in Korea?

Clinics like Gangnam J Urology Clinic offer the test in a patient-friendly and discreet setting:

 1. Initial Consultation
Your urologist will discuss your medical history, symptoms, and past treatments. If appropriate, they will explain how the NPT test works and schedule the procedure.

 2. Device Setup
You’ll be provided with a small, wearable monitoring device—typically a RigiScan or similar tool—that’s worn at the base and tip of the penis while you sleep. The device records:

• Erection frequency
• Rigidity
• Duration and timing of each event

 3. Testing Duration
The test is usually performed over 2 consecutive nights, either in the clinic or at home depending on the setup. Proper sleep is important for reliable results.

 4. Data Analysis & Interpretation
After the test, the recorded data is reviewed by your doctor. If normal nocturnal erections are present, the cause is likely psychological. If no erections are recorded, a physical cause is suspected and further testing or treatment is discussed.

What Do the Results Tell You?

• Normal erections during sleep: Suggest that the erectile tissue and blood vessels are functioning, pointing to psychological causes such as anxiety, depression, or stress.
• Absent or weak nocturnal erections: Indicate organic causes such as vascular disease, nerve damage, diabetes, or hormonal imbalances.

This distinction helps your doctor tailor your treatment plan—for example, focusing on counseling or medication in psychological cases, or recommending hormone therapy, shockwave therapy, or surgery in physical cases.

Why Choose Gangnam J Urology Clinic for NPT Testing?

• Specialized Urologists: Experienced in sexual health diagnostics and male reproductive medicine
• Modern Equipment: Clinics use FDA-approved and globally recognized devices for accurate measurement
• Discreet and Comfortable Testing: Option to perform the test at home in privacy
• English-Speaking Services: Helpful for foreigners seeking clear communication and guidance
• Integrated Treatment Planning: Follow-up options based on results, including further imaging or treatment

Cost of NPT Testing in Korea

With NHIS (if medically indicated):

• Doctor consultation and test: Typically ₩30,000–₩60,000 combined

Without NHIS (out-of-pocket):

• Consultation: ₩50,000–₩100,000
• NPT test (device rental and analysis): ₩100,000–₩200,000
• Total without insurance: ₩150,000 – ₩300,000+

Additional tests (such as hormonal panels or penile Doppler ultrasound) may be recommended depending on findings.

What Happens After the Test?

Depending on your results, the doctor may recommend:

• Psychological counseling or sex therapy
• Pharmacological treatments such as PDE5 inhibitors
• Hormonal therapy if low testosterone is found
• Further vascular evaluation, such as penile Doppler
• Penile shockwave therapy or intracavernosal injections for organic ED
• Lifestyle changes (weight loss, smoking cessation, sleep hygiene)



If you’re unsure why erectile dysfunction is happening, the Nocturnal Penile Tumescence test can bring valuable clarity. It’s a painless, non-invasive way to pinpoint the root cause—and lead you toward the most effective treatment. With advanced diagnostic tools and experienced specialists, Gangnam J Urology Clinic provides a supportive space for men to take charge of their sexual health and reclaim confidence—day or night.