The Noisy, Nighttime Factor That May Be Sabotaging Your Cholesterol
You may be doing everything right for your cholesterol, such as eating well, moving your body, and managing stress, but there's still might be one factor working against you. It's something that happens while you sleep.
New research points to something most of us have never considered: the noise outside your bedroom window. It's one of those little-known risk factors that can quietly affect your health without you realizing it.
A large-scale European study just found that nighttime traffic noise is linked to elevated cholesterol, LDL, and other lipid markers tied to heart disease. If you live in a city or on a busy street, this is worth paying attention to.
What the research found
The study, published in Environmental Research1, analyzed data from 272,229 adults across three European cohorts. Researchers looked at nighttime road traffic noise levels and compared them to blood-based metabolic markers.
What they found was striking: people exposed to nighttime traffic noise at or above 50 decibels had higher levels of total cholesterol, LDL cholesterol, intermediate-density lipoprotein (IDL), fatty acids, and other lipids. In total, 20 different metabolites showed large associations with noise exposure.
To put that in perspective, 50 decibels is roughly the sound of moderate rainfall or a quiet conversation. It's not jackhammer-level loud, but it's enough to affect your body while you're trying to rest.
Why nighttime noise hits your metabolism
Here's the key insight: you don't have to wake up for noise to affect you.
Even when you stay asleep, your body still hears what's happening around it. Traffic noise can disrupt your sleep architecture (the natural cycling between light sleep, deep sleep, and REM) without you ever consciously noticing.
Your ears don't have eyelids, so they're always on and always processing sound.When your brain registers noise during sleep, it can trigger a low-grade stress response. Your sympathetic nervous system activates, cortisol ticks up, and your body shifts into a subtle state of alertness. Over time, this chronic, low-level stress appears to influence lipid metabolism, specifically how your body processes and stores fats.
The researchers suggest this mechanism may help explain the well-documented link between traffic noise and cardiovascular disease.
How loud is too loud?
The study identified 50 decibels as the threshold where metabolic effects started showing up. Here's what that sounds like in real life:
- 40 dB: A quiet library or soft humming
- 50 dB: Moderate rainfall, a refrigerator running, or light traffic
- 60 dB: Normal conversation or background restaurant noise
- 70 dB: Busy traffic or a vacuum cleaner
If you can hear cars passing by while lying in bed, even faintly, you may be at or above that 50 dB mark.
Not sure where you stand? You can download a free decibel meter app on your phone and check your bedroom noise levels at night. It's a simple way to get a baseline.
What you can do about it
The good news is that this is a modifiable risk factor. Unlike genetics or age, your sleep environment is something you can actually change.
Here are some practical steps:
Assess your exposure
- Use a decibel app to measure nighttime noise in your bedroom
- Pay attention to when noise peaks, such as early morning traffic or late-night trucks
Create a sound buffer
- White noise machines or fans can mask intermittent traffic sounds and create a consistent audio backdrop (however, some recent research found pink noise from sound machines may reduce REM sleep, so it's a good idea to monitor your response)
- Sleep earplugs designed for comfort (like silicone or wax options) can reduce noise without feeling intrusive
Optimize your bedroom setup
- If possible, move your bed to the quietest wall, away from the street
- Heavy curtains or blackout drapes can dampen sound as well as light
- Consider weatherstripping windows or adding a window insert for extra sound insulation
Think long-term
- If you're moving or renovating, bedroom placement matters. Prioritize rooms that face away from busy roads.
- Double-pane windows make a noticeable difference in urban environments
The bottom line
You can't always control where you live or what's happening outside your window. But you can take steps to protect your sleep environment, and it turns out your metabolic health along with it.
This isn't about panic; it's about awareness. Nighttime noise is one more piece of the cholesterol puzzle, and now you know to look for it.
Your next step: Tonight, take a quick decibel reading in your bedroom. If you're consistently above 50 dB, start with one buffer (a white noise machine, earplugs, or heavier curtains) and see how it feels.