Introduction
If you’ve ever taken melatonin to help with sleep, you might wonder how scientists figure out whether it actually works. Melatonin, a neurohormone that regulates the sleep–wake cycle, is commonly studied and used as a therapy for symptoms like sleep problems, jet lag, delayed sleep phase issues, and even adjunctively in autism spectrum or neurodegenerative symptoms.
When conducting scientific studies with melatonin, a critical methodological decision involves choosing the most appropriate tool to measure sleep: Polysomnography (PSG) vs Actigraphy (ACTG).
What Are We Measuring in Melatonin Studies?
Melatonin influences:
- Sleep latency – Time to fall asleep
- Sleep efficiency – Percentage of time one is actually asleep when lying in bed
- Total sleep time – Total time one sleeps
- REM latency – Time to reach dream sleep (REM) after lying in bed
- Circadian alignment (DLMO – dim light melatonin onset) – When the brain starts making melatonin in response to dim light
Hence, the chosen tool must accurately capture these endpoints, especially in short-term, phase 2–3 studies. Polysomnography is like a full hospital check-up for sleep, while actigraphy is like a smartwatch that tracks your sleep at home.
Polysomnography (PSG): The Gold Standard
Pros:
- Comprehensive: records brain waves, eye movement, muscle activity, ECG, respiratory effort, SpO₂, and more
- Gold standard for diagnosing sleep apnoea, PLMD – Periodic limb movement disorder, daytime sleepiness and assessing REM architecture (dream sleep architecture)
- Ideal for studies needing detailed sleep stage analysis
Cons:
- High cost and needs more resources
- Requires overnight lab stay (artificial sleep setting)
- Poor scalability for large or longitudinal studies
- May not reflect habitual sleep patterns in home settings
Actigraphy (ACTG): The Pragmatic Alternative
Pros:
- Wearable, lightweight, and non-invasive
- Ideal for longitudinal studies in naturalistic environments
- Captures habitual sleep patterns over days to weeks
- Cost-effective and scalable
- Accepted by FDA and EMA for circadian rhythm disorder studies
Cons:
- Inferred data from motion, lacks granularity of sleep stages
- Cannot detect sleep phases or respiratory events
- Less accurate in users with movement disorders or fragmented sleep
Comparison Table
| Parameter | Polysomnography (PSG) | Actigraphy | Advantage | Scientific Use Case |
| Accuracy | High (Gold standard) | Moderate | Polysomnography | Diagnosis of sleep apnoea, daytime sleepiness |
| Cost | High (₹10,000–₹30,000 per night) | Low (₹2,000–₹5,000 per week) | Actigraphy | Long-term sleep tracking, large populations |
| Setup | Complex (requires lab & technician) | Simple (wrist-worn device) | Actigraphy | Home-based studies |
| Data Collected | Brain waves, muscle movement, eye movement, ECG, SpO₂, etc. | Movement (actimetry) | Polysomnography | Detailed brain and lung studies |
| User Comfort | Low (lab environment) | High (natural environment) | Actigraphy | Paediatric and geriatric users |
| Monitoring Duration | Single night | Multiple days/weeks | Actigraphy | Sleep problems or circadian rhythm disorders |
Conclusion
Both polysomnography and actigraphy have clear roles in scientific studies involving melatonin, but their application depends on study objectives, budget, and user population. For most wellness, circadian rhythm, or sleep problems-related research with melatonin, actigraphy offers a pragmatic and validated solution, while PSG remains essential when detailed sleep architecture is crucial. Clinicians and researchers are encouraged to adopt a hybrid or tiered approach, leveraging actigraphy for large-scale screening or longitudinal monitoring, and reserving PSG for diagnostic confirmation or complex cases.
Medical Disclaimer: This article has been written by a licensed medical professional and is intended for general informational purposes only. It does not substitute for personalised medical advice, diagnosis, or treatment. Readers should always seek the guidance of a qualified healthcare provider with any questions regarding a medical condition or health objectives. Never ignore or delay seeking medical advice based on information presented here.
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Evidence from Literature
- De Crescenzo, F., et al. (2020). The use of actigraphy in the monitoring of sleep and activity in attention problems: A meta-analysis. Sleep Medicine Reviews, 50, 101247.
- Braam, W., et al. (2009). Exogenous melatonin for sleep problems in individuals with intellectual disability: A meta-analysis. Developmental Medicine & Child Neurology, 51(5), 340–349.
- Smith, M. T., et al. (2018). Use of actigraphy for the evaluation of sleep disorders and circadian rhythm sleep–wake disorders: An AASM clinical practice guideline. Journal of Clinical Sleep Medicine, 14(7), 1231–1237.
- Ancoli-Israel, S., et al. (2003). The role of actigraphy in the study of sleep and circadian rhythms. Sleep, 26(3), 342–392.
- Sadeh, A., & Acebo, C. (2002). The role of actigraphy in sleep medicine. Sleep Medicine Reviews, 6(2), 113–124.
Last Updated on July 29, 2025
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