A recent study from Tulane University highlights the health risks associated with sleeping in light, linking it to cardiovascular diseases and sleep disruption.
A new study conducted by researchers at Tulane University has raised significant concerns about the health implications of sleeping with a light on. The research indicates that exposure to more than 3 lux of light—approximately the brightness of moonlight—correlates with an increased risk of serious cardiovascular conditions, including heart failure, atrial fibrillation, heart attack, stroke, and cardiovascular death.
Experts have weighed in on the potential dangers of nighttime light exposure. According to Dr. Chelsie Rohrscheib, a sleep expert and neuroscientist based in Michigan, sleep is largely regulated by the circadian rhythm, which serves as the brain’s internal 24-hour clock. “The circadian rhythm is strongly influenced by light entering the eyes,” she explained. “Light exposure signals the brain to suppress melatonin production, a hormone that helps regulate the timing of sleep, while low light levels signal the brain to produce more melatonin.”
As melatonin levels rise in the evening, they prepare both the brain and body for sleep. However, light pollution from various sources in the bedroom can trick the brain into producing less melatonin, negatively impacting sleep quality. “Consistent light exposure will chronically reduce overall sleep quality,” Rohrscheib warned.
Sleep plays a crucial role in numerous biological processes, including body and brain restoration, hormone release, immune system functioning, cognitive processes such as memory consolidation, brain waste clearance, and metabolic regulation. “When sleep is consistently poor, these processes do not function optimally, which in turn elevates the risk for many chronic health conditions such as hypertension, cardiovascular disease, stroke, type 2 diabetes, obesity, neurodegenerative diseases, certain cancers, and mood disorders,” she added.
A separate study conducted by Northwestern Medicine in 2022 found that even one night of sleeping with moderate light exposure (100 lux) disrupted glucose regulation, increased heart rate, and heightened sympathetic nervous system activity, as evidenced by reduced heart rate variability (HRV).
Dr. Ashley Curtis, a sleep researcher and assistant professor at the University of South Florida College of Nursing, noted that sleep impairment is also linked to an increased risk of mortality. “Emerging evidence even suggests that it affects the gut microbiome, impacting everything from digestion to immunity,” she stated. “While the immediate evidence is strongest for disrupted sleep health, the downstream risks to your long-term health are substantial.”
Experts agree that certain groups may be more sensitive to nighttime light than others. “Shift workers, children, older adults, and individuals with insomnia or mood disorders are especially vulnerable to the effects of light on sleep depth,” said Dr. Alex Dimitriu, a double board-certified sleep medicine doctor and founder of Menlo Park Psychiatry & Sleep Medicine.
Curtis pointed out that older adults often become less sensitive to light, meaning bright or short-wavelength light has a weaker effect on suppressing melatonin compared to younger adults. “The caveat, however, is that older adults also experience a higher baseline prevalence of sleep disruption, which can bidirectionally impact the circadian system,” she added.
There is also evidence suggesting that bright light has a more pronounced impact on melatonin suppression in men. For individuals with insomnia, who already face chronic sleep disruption, exposure to bright light before bedtime can exacerbate these underlying issues, further interfering with the biological circadian rhythm.
Dr. Dimitriu noted that blue wavelength light emitted from TVs and phones is particularly disruptive because people’s retinas are most sensitive to it, leading to maximal melatonin suppression. “Dim, warm, red-toned night lights cause far less circadian impact—these are natural sunset colors one would see in the evenings,” he explained.
Curtis concurred, stating that warmer, dimmer light, which has a longer wavelength, does not significantly impact melatonin production. “Research shows that even if dim light impacts melatonin initially, it allows time for the body to recover,” she said. “Therefore, it doesn’t disrupt your sleep to the degree that brighter light does.”
While blackout curtains are often recommended for optimal sleep, Curtis emphasized that complete darkness is not necessary to maintain a healthy sleep environment. Experts suggest implementing various changes to create a conducive sleep atmosphere, even if it is not pitch black.
These findings underscore the importance of being mindful of light exposure during sleep, as it can have far-reaching effects on overall health and well-being, according to Fox News Digital.