With the widespread adoption of LED lighting in homes, workplaces, and digital devices, concerns about the health effects of LED flicker have gained attention. The IEEE 1789-2015 standard, titled “Recommended Practices for Modulating Current in High-Brightness LEDs for Mitigating Health Risks to Viewers”, provides critical guidelines for manufacturers and lighting professionals to reduce risks associated with LED flicker. This blog post explores the standard in detail—what it is, why it matters, and how it impacts the future of LED lighting.
What Is IEEE 1789-2015?
IEEE 1789-2015 is a technical standard developed by the Institute of Electrical and Electronics Engineers (IEEE) to address the potential health hazards of flicker caused by modulated current in LED lighting systems. Flicker—especially invisible or imperceptible flicker—has been linked to a variety of health issues, including:
Eyestrain
Headaches
Migraines
Seizures (particularly in photosensitive individuals)
General discomfort and fatigue
The goal of this standard is to help manufacturers and engineers design LED systems that minimize these risks by regulating how the electrical current driving the LEDs is modulated.
Why LED Flicker Is a Problem
Unlike incandescent lights, LEDs respond almost instantaneously to changes in electrical current. When current is modulated to control brightness (a process known as Pulse Width Modulation (PWM)), the rapid switching can cause visible or invisible flicker.
While visible flicker is easier to notice and avoid, invisible flicker (typically above 100 Hz) can still have physiological and neurological effects. IEEE 1789-2015 addresses both types of flicker and sets frequency-based guidelines to mitigate them.
Key Recommendations in IEEE 1789-2015
The IEEE standard provides a risk-based framework that relates the modulation frequency and the percentage of flicker (modulation depth) to potential health effects. Here are the core recommendations:
1. Flicker Frequency Matters
Low-frequency modulation (<90 Hz): High risk. Avoid if possible.
Medium frequency (90–1250 Hz): Acceptable depending on modulation depth.
High-frequency modulation (>1250 Hz): Generally considered safe.
2. Modulation Depth (Percent Flicker)
The standard defines modulation depth as:
IEEE 1789-2015 includes two curves:
No Observable Effect Level (NOEL): Below this line, the flicker is considered safe.
Low-Risk Level: Between NOEL and a higher threshold where some sensitive individuals may experience effects.
Designers are encouraged to stay below the NOEL curve or, at the very least, within the low-risk zone.
Applications and Implications
✅ Lighting Design
Architects and lighting engineers should prioritize LED drivers and dimmers that comply with IEEE 1789-2015 recommendations. Especially in schools, hospitals, and offices, where people spend long hours under artificial lighting.
✅ Consumer Electronics
Display manufacturers can mitigate flicker by using high-frequency PWM or constant-current dimming techniques, especially in smartphones and monitors used for extended periods.
✅ Smart Lighting and IoT
As smart lighting systems grow, ensuring they operate at safe modulation frequencies is key to maintaining user health and comfort.
How to Comply with IEEE 1789-2015
➤ Use Flicker-Free LED Drivers
Choose constant current LED drivers with low ripple or high-frequency modulation above 1250 Hz.
➤ Measure Flicker Properly
Use photometric measurement tools like flicker meters or oscilloscopes with photodiodes to measure flicker frequency and depth.
➤ Specify Standards in Procurement
When sourcing lighting products, request compliance documentation showing that the design adheres to IEEE 1789-2015 recommendations.
Limitations and Future Outlook
While IEEE 1789-2015 is not a mandatory regulation, it is increasingly becoming a benchmark in lighting quality. Some critics argue the standard is conservative, but as more research emerges, future versions may include more granular health impact data and real-world usage considerations.
Additionally, the standard does not cover all possible health outcomes—only those associated with flicker due to current modulation. Colour temperature, blue light hazard, and circadian rhythm effects are separate concerns addressed in other standards.