Love Falling Asleep With The TV On? It’s Not Just Impacting Your Sleep
Most of us know that light exposure at night can disrupt our sleep, but it’s also what lets us stay up a little later to finish a show, scroll through our phones, or read one more chapter before bed.
Yet new research presented at the American Heart Association’s 2025 Scientific Sessions suggests that artificial light at night may influence our health in deeper ways than we realize, affecting not just our sleep, but our stress levels, our arteries, and our long-term heart health.
As someone who’s guilty of late-night TV (and the occasional scroll far past bedtime), it was a good reminder that light isn’t just about sleep; it’s also a cue that directly influences how our hearts and brains function.
Inside the study
To better understand how nighttime light exposure might affect the body, researchers analyzed brain scans and medical records from more than 450 adults without existing heart disease. Using PET/CT imaging, they were able to observe both brain stress activity and arterial inflammation, two biological markers that often appear years before cardiovascular disease develops.
Then, they mapped how much artificial light each participant was exposed to at night based on their home address.
Here’s what they found:
- People exposed to higher levels of artificial light at night showed increased stress-related brain activity, particularly in regions that activate the body’s “fight-or-flight” response.
- This brain activity correlated with greater inflammation in the arteries, a key early driver of heart disease.
- And over time, these biological signals translated into a significantly higher risk of cardiovascular events.
The brain seems to interpret nighttime light as a form of stress, kicking off a cascade that can quietly wear down the heart.
Why light at night stresses your system
Most of us already know that light affects melatonin, the hormone that tells your body it’s time to sleep. But melatonin is only part of the story. When your brain perceives light at night, it does more than suppress melatonin; it activates the sympathetic nervous system, the part of your physiology that keeps you alert and ready to respond to stress.
That’s useful when you’re navigating a real threat, but less ideal when you’re lying in bed trying to rest. Over time, chronic activation of this “fight-or-flight” response can lead to inflammation, elevated blood pressure, and stiffer arteries, all of which increase cardiovascular risk.
How to protect your heart (& your circadian rhythm)
The takeaway isn’t to live in darkness; it’s to become more intentional about the light you allow into your nights. Here’s how to start:
- Make your bedroom a dark zone. Blackout curtains or a simple eye mask can block streetlight glow or the flicker from passing cars. Even dim light can disrupt your body’s nightly repair processes.
- Rethink your bulbs. Switch to warm, amber-toned lighting in the evening. Save the bright, blue-white LEDs for daytime when you want to feel alert.
- Give your devices a curfew. Phones, tablets, and TVs emit blue light that keeps your brain in daytime mode. Try setting a “digital sunset” an hour before bed to help your body wind down naturally.
- Be mindful of outdoor lighting. If you have exterior lights, use motion sensors or timers to reduce unnecessary brightness. It’s better for your health (and your energy bill).
These small shifts might seem simple, but light exposure is one of the few environmental stressors we can directly control.
The takeaway
Artificial light at night doesn’t just interfere with your sleep; it may quietly strain your cardiovascular system in ways that build up over time. This new research adds to decades of evidence connecting circadian disruption with chronic disease, underscoring that protecting your heart might start with something as simple as turning off the lights.