Studies indicate that even moderate ambient lighting exposure during sleep, in contrast with sleeping in dimly lit rooms, causes adverse impacts to cardiovascular function and increases insulin resistance the next morning.
These study results demonstrate that even one night of moderate lighting exposure while sleeping can disrupt cardiovascular and glucose regulation, risk factors associated with diabetes, heart disease and metabolic syndrome. Therefore it is advised that individuals minimise or limit the amount of light exposure while sleeping.
There’s ample evidence that daytime light exposure increases heart rate through sympathetic nervous system activation, increasing heartbeat rate and alertness to meet daytime challenges. According to this study, similar results can also be observed when light is exposure during sleeping at night.
Researchers demonstrated an increase in heart rate when study participants slept in moderately lit rooms, due to autonomic nervous system activation during sleep; thus leading to increased cardiovascular parameters during daytime but decreased at nighttime.
There are parasympathetic and sympathetic nervous systems which regulate our physiology throughout the day and night, respectively. Sympathetic systems provide daytime regulation while parasympathetic provides restorative benefits at nighttime.
Researchers found that participants experienced insulin resistance upon awakening in a moderately lit room after sleeping. Insulin resistance occurs when muscle, liver and fat cells don’t respond as expected to insulin and can’t use glucose from blood for energy production; to compensate, pancreas produces more insulin which raises blood sugar over time.
Research had discovered a correlation between those exposed to light while sleeping and an increase in obesity and weight gain, suggesting a possible mechanism of why they gained more weight than expected. The current research shows how light exposure impacts glucose regulation mechanisms that control body glucose, possibly explaining their weight gain.
While study participants weren’t conscious of their bodies’ biological changes at night, their brains nonetheless noticed. Their brains responded similarly to someone experiencing light or fragmented sleep – signifying that sleep physiology wasn’t resting as it should.
Sleeping with artificial lighting at night from indoor light-emitting devices or external sources is becoming more and more prevalent, particularly in large urban areas. A significant percentage of people sleep with either their bedroom lights on or the TV on while sleeping.
As well as sleep, exercise and nutrition, daytime light exposure is an essential health factor, yet the researchers found that even modest light intensities at nighttime can impair endocrine and cardiovascular measures.
Researchers conducted experiments comparing sleeping under moderate light of 100 lux compared to sleeping in dim light of 3 lux over one night in individuals. They discovered that when exposed to moderate light, exposure caused a higher state of alert in individuals’ bodies; their heart rates rose and their force of heart contractions increased, along with how quickly blood traveled into blood vessels for oxygenation.
These results are especially relevant to individuals living in modern environments where indoor and outdoor nighttime lighting exposure has become more frequent.
