Is your nightly TV habit harming your heart? New study reveals the hidden dangers of sleep light

Sleeping with the TV on may harm your heart health; new research reveals how nighttime light exposure disrupts sleep and alters heart structure.

Do you often fall asleep with the television still playing in the background? Our body has an internal clock called the circadian rhythm. This rhythm responds strongly to light and darkness. Darkness signals that it is time to wind down and supports the natural release of melatonin, a hormone that helps regulate sleep. Artificial light at night can interfere with this process.

Is sleeping with the TV on bad for your heart? (Adobe Stock)

By Tavishi Dogra

Tavishi Dogra is a Deputy Chief Content Producer, Health & Wellness, at Hindustan Times. She has over 9 years of experience writing about fitness, nutrition, and mental well-being, translating medical research and expert insights into practical advice readers can trust.

Career journey and experience
Tavishi began her health journalism journey in 2017, and has since reported for RSTV, Financial Express, Jagran, HT Media Labs and Zee. She joined Hindustan Times to simplify wellness subjects by cutting through jargon.

From decoding health trends and interviewing doctors to testing fitness routines herself, Tavishi always approaches content with one filter: “Will this help someone make a better decision today?”

Subject expertise
With 9+ years tracking India’s health conversations, Tavishi knows the gap between clinical advice and daily life. She knows fads from fundamentals and curates science-backed, expert-recommended solutions.

In fitness, she breaks down bodyweight training, recovery, and posture fixes for desk-bound readers. In nutrition, she translates guidelines into affordable, desi meal tweaks. In mental well-being, she focuses on stigma-free, actionable tools — all backed by research, expert input, and lived context.

Education and professional background
Tavishi holds a Master’s degree in Journalism and Mass Communication and began her career reporting on public affairs for broadcast. Those early years in policy and TV shaped how she writes today: fast, factual, and human-first.

Editorial Philosophy
I write with one single goal: To simplify health in a world full of noise by finding what’s actually doable, safe, and evidence-based for my readers. I test claims against research and user experiences. When all else fails, I speak to the expert who sees 50 patients a day, not the one with the most followers.

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New research adds another reason to take nighttime light seriously

A study published in the European Heart Journal examined 11,071 UK Biobank participants who wore a wrist device with a light sensor. About three years later, they underwent cardiovascular MRI scans, allowing researchers to closely examine the heart's structure and function.

• The researchers compared people with different levels of nighttime light exposure.
• Those exposed to light levels above 3 lux showed measurable differences in their hearts.
• Their left ventricular mass was 2.4% higher, average wall thickness was 1.5% greater, and myocardial contraction fraction was 1.9% lower.
• Changes were also seen in the right ventricle and left atrium. The overall pattern was described as concentric cardiac remodeling.

Explaining these findings, “This study shows that greater exposure to light at night was associated with measurable differences in heart structure and function. We should take that association seriously. Even a minimal light exposure can affect you. This is not limited to television viewing specifically. Light sources can include TVs, streetlights, lamps, and other sources," Dr Anil (Col) Dhall, Head of the Department, Cardiology, Shalby International Hospital, Gurgaon, tells Health Shots.

Another interesting part of the findings is this

Shorter sleep duration statistically explained a substantial part of the association between nighttime light and the cardiac changes. In other words, sleep itself may be an important part of the story. The researchers estimated that shorter sleep duration statistically mediated around 24% to 49% of the observed associations.

“The real concern may not be the television itself. It is the disruption of the natural nighttime environment, light exposure, disturbed sleep, and the effect these may have on our body clock. We still need more research to understand exactly how much each of these factors contributes,” says Dr (Col) Anil Dhall.

Why shouldn't you put a TV in your bedroom?

You do not necessarily need to throw the television out of your bedroom. But if you use it to fall asleep, set a sleep timer rather than leaving it on all night. Keep unnecessary lights off, reduce screen exposure close to bedtime, and use curtains or blinds to block bright outdoor light.

(Disclaimer: This article is for informational purposes only and is not a substitute for professional medical advice. Always seek the advice of your doctor with any questions about a medical condition.)