The Case For Sleeping In Total Darkness (Nope, Not Even A Night Light)
You know those little glowing lights in your bedroom—the humidifier, sound machine, or charger? They may seem harmless, but research suggests even subtle nighttime light could be interfering with your health in ways you don’t realize.
Nix the light
We already know that bright light disrupts melatonin, the hormone that helps regulate sleep. But new findings show that even very dim light, the kind that lets you see your way around the room but is too faint to read by, can impact cardiometabolic health, which includes heart, blood sugar, and metabolic function.
Given how much time we spend indoors surrounded by artificial light, this is a relevant reminder that our sleep environments matter.
A look into the study
The study tracked healthy adults sleeping in dim light versus moderate room light. Results showed that even one night of soft illumination had measurable effects:
- Higher heart rate during sleep
- Lower heart rate variability, a marker of recovery and resilience
- Increased insulin resistance the next morning, which over time can raise diabetes and heart disease risk
- No significant melatonin changes, suggesting the effects weren’t about sleep hormones but rather nervous system activation
What you can do
The good news is that this is one of the simplest health upgrades you can make. Block out or cover small light sources, choose blackout curtains, and aim to keep your sleep space as dark as possible.
The takeaway
Your bedroom doesn’t have to look like a blackout cave, but the darker, the better. Even tiny glows from chargers or devices can quietly stress your heart and metabolism. Make darkness a priority, and you’ll be investing in deeper sleep and stronger long-term health.