It turns out that this type of lamp can make people gain weight.

These past few days, a trending topic has set the lighting industry abuzz—“Turns out this kind of light can make you gain weight.”

Let me state my conclusion upfront: the blame doesn’t lie with the lights themselves. But if you have these three types of lamps in your home tonight, you really should turn them off.

First, let’s get the facts straight. The trending story claimed that LED lights from certain companies suppress melatonin and insulin, leading to weight gain.

Doctors at top-tier hospitals clarified very clearly: it’s not the lights themselves that are problematic; rather, it’s “when, how long, and what color” of light exposure that causes issues. Bright, bluish-white light at night tricks the eyes—and the brain—into thinking it’s still daytime. With reduced melatonin, insulin sensitivity drops, cortisol levels rise, and people become more prone to craving high-calorie foods. This is because light disrupts the circadian rhythm, not because there’s something fattening added to the bulbs. So normal office lighting during the day generally won’t cause problems; what truly needs guarding against is nighttime light.

Even more interesting is the reverse claim. A study published in Cell Metabolism recruited 13 patients with type 2 diabetes and had them spend about four days each in an artificial-light office and a natural-sunlight office, separated by a month. Diet, activity, and sleep were kept identical—the only variable was the light. What were the results? The time spent maintaining target blood sugar levels rose from 43.3% to 50.9%, equivalent to nearly two extra hours of stable blood glucose per day, while the body also became better at burning fat.

You see, used correctly, light is medicine; used incorrectly, it becomes a burden.

In recent years, Lao Hong has been researching Healthy Lighting, and he’d like to remind everyone to do three things starting tonight:

First, dim the room lights to low-color-warmth mode half an hour before bed;

Second, if you must get up at night, leave on low-power, warm-colored, under-bed-level lights—ideally installing multiple automatic sensor‑activated low-level nightlights along the route to the bathroom, ensuring no direct light shines into your eyes;

Third, unplug those little white or blue indicator lights on chargers, set-top boxes, and air purifiers whenever possible; otherwise, cover them. Remember, more light isn’t necessarily better—it’s the right kind of light at the right time that matters. Lights are tools: shining at the right moment promotes health, while shining at the wrong moment becomes a burden.

I’m Lao Hong. I don’t judge lights by price, only by whether the right kind of light is being used at the right time. How many “little bright spots” do you have in your bedroom? Share the number in the comments, snap a photo, and Lao Hong will help analyze whether you’re using them correctly!

Follow Lao Hong on Light Talk to illuminate your path forward!

About the Author, Hong Bing:

Hong Bing currently serves as Editor-in-Chief of China Light Net & Agricultural Lighting Net, the official websites of the China Illuminating Electrical Appliances Association; Executive Dean of Ming Classroom; Executive Vice President of the Beijing Illuminating Electrical Appliances Association; Deputy Director of both the Talent Training Committee and the Agricultural Lighting Professional Committee of the China Illuminating Electrical Appliances Association; Executive Deputy Director of the Lighting Alumni Association of Fudan University; and Board Member of the Ecological Environment Alumni Association of CEIBS. He graduated from the Department of Light Sources and Lighting Engineering at Fudan University in 1991 and earned an MBA from CEIBS in 2003. He has held positions in R&D, product planning, and marketing at institutions including the China Building Materials Academy, Panasonic, GE, and OSRAM. In 2008, he received the Siemens Global Top Plus Award and the Siemens China Excellence Performance Award, and in 2009 founded China Light Net.

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