ISLAMABAD, Sep 5(ABC): A study from Northwestern University Feinberg School of Medicine in Chicago explores the link between light exposures during sleep and health risks. The research serves as a warning for the many people living in industrialized nations where light tends to be omnipresent.
Sleeping while exposed to any type of light whatsoever — even dim light — is linked to an increase in the likelihood of obesity, diabetes, and hypertension (high blood pressure) in older adults, the study finds.
Corresponding author for the study, Dr. Minjee Kim, of Northwestern Medicine Feinberg School of Medicine, said in a press release: “Whether it be from one’s smartphone, leaving a TV on overnight, or light pollution in a big city, we live among an abundant number amount of artificial sources of light that are available 24 hours of a day.”
“It appears that even a tiny amount of light has a noticeable effect on our body’s response,” Dr. Kim told Medical News Today.
“Previous animal and some human studies have suggested a potential association between mistimed light — not enough light during the day, too much light at night — and obesity,” said Dr. Kim.
“There was little data on light exposure patterns in older adults,” said Dr. Kim. “Since older adults are already at increased risk of cardiovascular diseases, we wanted to know how frequently older adults are exposed to ‘light at night’ [or “LAN”], and whether light at night is correlated with CVD risk factors.”
It is not only older people whose health may be affected by not sleeping in deep darkness.
“In a previous study done by our group, even one night of dim light exposure during sleep raised heart rate and blood glucose in young, healthy adults who were brought into a sleep lab for an overnight experiment,” Dr. Kim explained.
Dr. Jonathan Cedernaes, a sleep expert from Uppsala University in Sweden, who was not involved in either study, told MNT:
“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 was published in the journal Oxford Academic SLEEP.
A real-world study
Unlike the group’s previous research, the new study observed the real-world effects of LAN, tracking the sleep of 552 older men and women.
“In the current study, we measured light exposure and sleep in older adults (ages 63-84) for seven days using a wrist-worn device. Instead of bringing these older adults to the sleep lab, we collected data in their routine environments,” said Dr. Kim.
They found that less than half of these older adults slept in a pitch-black room for at least five hours.
“We were frankly surprised to find out that more than half of the older adults were sleeping with some light at night,“ Dr. Kim said. “Adults who slept with some light during their sleep period were generally exposed to dim light.”
The researchers found that the likelihood of developing high blood pressure (hypertension) was increased by 74%, obesity by 82%, and diabetes by 100%. Participants were also tested for an increased risk of hypercholesterolemia, but no difference was observed.