A new study has said that exposure to even dim light while sleeping at night is associated with a higher risk of obesity, diabetes, and high blood pressure in older adults. As such, the study from Northwestern University Feinberg School of Medicine in Chicago further highlighted the link between light exposure during sleep and health risks.
Published in Oxford Academic Sleep, the study analysed 552 community-dwelling adults aged 63-84 who underwent an examination of CVD (cardiovascular) risk factor profiles and 7-day actigraphy recording for activity and light measures.
Corresponding author for the study, Dr Minjee Kim, of Northwestern Medicine Feinberg School of Medicine, told medicalnewstoday, “The fact that this is observed in older people may represent the more cumulative effects of such a mechanistic relationship, meaning that the adverse cardiometabolic effects of nighttime light exposure may become more evident over time (meaning in more advanced age, if one maintains such a lifestyle or exposure pattern over years to decades).”
The study noted that LAN (light at night) exposure was associated with a higher prevalence of obesity (multivariable-adjusted odds ratio (OR) 1.82 (95% CI 1.26-2.65)), diabetes (OR 2.00 (1.19-3.43)), and hypertension (OR 1.74 (1.21-2.52)) but not with hypercholesterolemia. LAN was also associated with (1) later timing of lowest light exposure (L5-light) and lowest activity (L5-activity), (2) lower inter-daily stability and amplitude of light exposure and activity, and (3) higher wake after sleep onset.
Here’s what to know
Fragmented sleep may be greatest in the few hours before waking up, said Dr Rakesh Rajpurohit, MD consultant pulmonologist and critical care medicine specialist from Jain Multispecialty Hospital, Mira Road, Mumbai. “Pitch darkness, hence, reduces potential distractions and disruptions to sleep,” he said.
Light exposure tends to alter the body’s internal sleep clock — the biological mechanism that regulates sleep-wake cycles and also interferes with both the quantity and quality of sleep, explained Dr Aniket Mule, consultant internal medicine, Wockhardt Hospitals Mira Road.
“So, when the room is completely dark, the body produces a hormone called melatonin that helps to fight diseases, including breast and prostate cancer. Complete darkness will also make it easy for you to sleep peacefully. It not only helps to reduce the risk of obesity, diabetes, and high blood pressure but even depression,” Dr Shah told indianexpress.com.
He added that sleeping in pitch darkness “helps your eyes rest properly and protects them, too”.
However, if you are not in the habit of sleeping without lights, it is best to “keep your lights dim when preparing for bed“. Using a small, low-power lamp can help transition to bedtime and ultimately, pitch darkness. Low-illuminance and warm colour temperature, preferably closer to the floor, may help with relaxation and getting into the right mindset for sleep, said Dr Rajpurohit.