PROLED MacBook Pro flicker linked to headaches and eye strain

What buyers are reporting

Some new owners of the PROLED MacBook Pro say the display is causing eye strain, headaches and dizziness, according to AppleInsider. The publication reports that Genius Bar staff are receiving complaints and that some retailers are seeing a slightly higher than normal rate of returns, though this claim is unverified.

AppleInsider says the problem is not obvious flicker, such as a flashing light at a party. Instead, the screen is said to be strobing constantly at close range, at a combination of frequency and brightness swing that affects some users.

What pulse width modulation is

Pulse width modulation, or PWM, is a way of controlling brightness by switching a light on and off very quickly. In an OLED display, each colour cell is turned on and off at high speed. A cell that is on half the time appears about half as bright, a setting known as a 50% duty cycle.

This differs from an old incandescent bulb, which simply emits less light when given less power and does not strobe. PWM has been used in OLED iPhones since the iPhone X and is essential to how those screens work. On a phone the affected area of vision is small, but a laptop screen covers a much wider field of view.

The numbers behind the display

According to AppleInsider, the new MacBook Pro's pulse width modulation runs at 240Hz with a 56% flicker amplitude. That matches modern iPhones, but on a much larger panel.

For comparison, the publication notes that the M4 Pro Mini-LED MacBook uses a much higher modulation frequency of 14,880 Hz, which it says is better for nearly everybody. PWM also exists in some non-OLED screens, so the technology itself is not unique to OLED panels.

Who may be affected

AppleInsider describes three main health effects linked to strobing lights. Flicker vertigo, which occurs at refresh rates between 1Hz and 20Hz, can cause disorientation, nausea and rapid eye movement. It was first observed in early helicopters, when sunlight strobed through rotating blades.

Photosensitive epilepsy is rarer but far more serious, since any strobing can trigger a seizure in susceptible people, some of whom may not know they have the condition. Other groups reported to be more sensitive include people with migraines, tension or cluster headaches, traumatic brain injuries, or photophobia, a heightened sensitivity to light.

The publication notes that sensitivity varies and is worsened by fatigue, diet and long exposure. A rested user may notice nothing, while someone who has skipped meals and lost sleep is in the worst-case situation.

What to do if symptoms appear

AppleInsider says the advice from the doctors it consulted, and from Apple itself, is simple: if you start feeling unwell while using the device, stop using it. The publication is not written by medical professionals, so anyone with concerns about photosensitivity should speak to a doctor.

The article also points out that not everyone is affected, and that sensitivity to flicker frequencies differs from person to person. Given that LED light bulbs also flicker to some degree, most people tolerate this kind of lighting, but the publication argues the reports still deserve attention.