Your nightlight may help keep the monsters at bay, but it’s not without downsides. According to “Nighttime Light Exposure Is Linked to Heart Changes,” researchers analyzed UK Biobank participants who wore light-sensing fitness monitors for a week, then compared nighttime exposure with cardiac MRI scans taken before any diagnosed heart problems. People routinely exposed to at least 3 lux of light at night – roughly three candles from three feet away – tended to have thicker heart walls and less efficient pumping than those sleeping in darker conditions. The study shows correlation rather than causation, and researchers can’t rule out other factors, but it adds to earlier work linking nighttime light with higher rates of cardiovascular and metabolic problems. For now, getting your bedroom as dark as practical with blackout curtains, switched-off lights, or an eye mask looks like a sensible sleep-hygiene move. Darkness is only one piece of the setup. Our story “Control bedroom noise for better recovery” notes that experts generally recommend nighttime noise around 25 to 30 decibels, and deep sleep supports muscle repair and growth-hormone release. If hunger keeps you up, “Oatmeal could be the right late-night snack” suggests a small, low-sugar bowl can satisfy you without the heaviness of a high-fat meal, though finishing dinner at least three hours before bed may help avoid the problem altogether. And if heat is the culprit, “How to safely lower your body temperature for better sleep” offers options ranging from a lukewarm shower to the strange trick of chilling lightly damp socks before bed. Dark, quiet, cool, and comfortable is a pretty good recipe for giving your next run a better starting point.

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