Why Do Modern Light Bulbs Flicker? — and Does It Matter for Our Brains?

If you’ve ever slowed down a video on your phone and noticed your lights flickering wildly, you’re not imagining things. Many modern light bulbs do flicker, and some far more than others. The bigger question is: does it matter?

 

The answer is nuanced. Some flicker is normal and harmless. Other flicker is artificial, aggressive, and can stress the nervous system, especially in children and sensitive individuals like those with epilepsy.

 

Let’s break it down simply.

 

First: All light technically “flickers”.

 

In the U.S., household electricity runs on alternating current (AC) at 60 Hz. That means power reverses direction 60 times per second, creating a 120 Hz light ripple.

 

So yes, even incandescent and halogen bulbs show a tiny fluctuation if you record them on slow motion video.

 

But here’s the key difference:

Incandescent & halogen bulbs

 

  • Light is produced by a hot metal filament

  • The filament stays hot between cycles

  • Light output is smooth and continuous

  • The brain does not perceive this as flicker

 

What your phone sees is not what your nervous system experiences.

 

From a biological and neurological standpoint, incandescent and halogen bulbs are among the gentlest forms of artificial lighting.

 

Where problems begin: LEDs.

 

LEDs don’t glow from heat. They turn on and off electronically.

 

To work on household power, LEDs require a driver that converts AC to DC. The quality of that driver determines whether the light is smooth or stressful.

 

Cheap or poorly designed LEDs:

 

  • Pulse rapidly

  • Create high contrast on/off flicker

  • Can trigger headaches, eye strain, agitation, or fatigue

  • Are more noticeable to children and sensitive nervous systems

 

The worst offenders: “Vintage” LED filament bulbs

 

Those clear glass bulbs with visible yellow “filaments” look old-fashioned and are all the rage and totally on trend these days, but they are not incandescent.

 

They are actually:

 

  • Tiny LED strips inside glass

  • Minimal internal electronics

  • Little to no flicker smoothing

 

Because there’s no room for proper circuitry, many filament LEDs:

 

  • Flicker aggressively

  • Flicker even more when paired with dimmers

  • Appear especially bad on slow-motion video (for good reason)

 

These bulbs are decorative, not biologically friendly.

 

Why dimmers often make flicker worse

 

Most homes still use older TRIAC dimmers, designed for incandescent bulbs.

When paired with LEDs — especially filament LEDs — they can:

 

  • Chop the electrical waveform

  • Cause rapid micro-flicker

  • Create strobing effects the brain detects even if the eyes don’t

 

“Dimmable” on the box does not guarantee low flicker.

 

Children’s brains & sensitive nervous systems

 

Children’s brains are still developing their ability to filter sensory input. Constant low-level flicker can contribute to:

 

  • Restlessness

  • Reduced attention

  • Headaches or eye discomfort

  • General nervous system stress

 

People with migraines, autism, anxiety, concussion history, or epilepsy can be even more sensitive.

 

This doesn’t mean lighting causes disease, but lighting quality absolutely affects neurological comfort.

 

So what lighting is best?

Here are Some Best Options

 

  • Halogen bulbs (where available)

  • Traditional incandescent bulbs

  • High-quality, flicker-free LED bulbs

  • Frosted bulbs instead of clear

  • Warm color temperatures (2700–3000K)

  • High CRI (90+)

 

Lighting to avoid

 

  • Clear glass LED filament / Edison bulbs

  • Decorative “vintage” LEDs

  • Cheap LEDs with no flicker specs

  • LED + incompatible dimmer combinations

 

Why your phone test matters

 

Your slow-motion camera is actually a useful screening tool:

 

  • Severe flicker on camera = poor driver design

  • Rapid flicker is not safer than slow flicker

  • If it looks chaotic, your nervous system is likely compensating for it

 

Bottom line

 

Not all flicker is equal.

 

  • Incandescent and halogen flicker is natural and biologically benign

  • LED flicker is artificial and design-dependent

  • Decorative LED filament bulbs are some of the worst offenders

  • Better lighting can make a home feel calmer, quieter, and more comfortable — especially for children

 

Lighting isn’t just about aesthetics or energy efficiency.

It’s part of the environment your nervous system lives in every day.

 

And once you notice it, you can’t unsee it.

©

Laura HillComment