Nearly one-third of our lives is spent sleeping. While adequate sleep is essential for health, did you know that one small sleeping habit could be the reason you're gaining weight—and in severe cases, even increase cancer risk?So what exactly are the dangers of sleeping with the lights on?
Dr. Jared Bunch, an expert from the American Heart Institute, recently synthesized multiple studies in an article pointing out: Excessively bright bedroom lighting and prolonged "exposure" to light can trigger obesity, high blood lipids, sleep deprivation, and other issues, making it a risk factor for heart health.
Nighttime is the optimal period for skin metabolism. During this time, skin blood vessels fully dilate, allowing ample blood flow to the skin. With this blood supply, the skin undergoes self-repair and regeneration, helping prevent and delay skin aging. Thus, it's no exaggeration to say sleep is the ultimate beauty elixir!
Does sleeping with the lights on accelerate aging?Are you aware of these sleep pitfalls?
Staying up late = weight gain + accelerated aging
Dry skin, dehydration, pigmentation, dark spots, acne, and rough texture—all these issues are linked to insufficient sleep. Frequent late nights impair the skin's ability to retain moisture, self-repair, and regenerate. Simultaneously, slowed metabolism accelerates toxin buildup, hastening skin aging.A U.S. study also reveals that sleep deprivation directly impacts endocrine function. Insufficient female hormone secretion can make skin appear at least ten years older.
When women lose sleep, their "indulgence" hormones surge rapidly, driving increased food intake and fueling cravings for chocolate, cookies, and candy.
Conversely, during deep sleep, the brain quietly secretes large amounts of growth hormone. This hormone directs the body to convert excess fat into energy, preventing fat accumulation on the hips, thighs, and abdomen. This is why many people attempt to achieve weight loss through adequate sleep.This pigment reaches peak secretion between 11 PM and 1 AM, ceasing production after dawn. This process not only suppresses sympathetic nervous system activity but also lowers blood pressure and slows heart rate, allowing the heart to rest and recover. Additionally, it possesses anti-cancer properties.
A key characteristic of the pineal gland is that melatonin production ceases whenever the eyes detect light. While eyelids partially block light sources, leaving lights on still allows light perception.
Therefore, sleeping with the lights on suppresses melatonin secretion, severely compromising sleep quality and significantly weakening immune function. Melatonin secretion not only inhibits sympathetic nervous system activity but also lowers blood pressure, slows heart rate, allows the heart to rest and recover energy, and even helps eliminate cancer cells.
Sleeping with the light on increases babies' risk of myopia
Babies often fear the dark, so many parents leave a nightlight by their child's bedside. While this may seem cozy, it hides significant health risks. Researchers have found that bedside lighting not only disrupts babies' sleep quality but may also trigger various health issues, posing serious threats to their well-being.Recent studies reveal that any artificial light source generates subtle light pressure. Under this influence, babies become restless and agitated, making it difficult for them to fall asleep. Additionally, prolonged exposure to light while sleeping may disrupt the reticular activating system, shortening sleep duration, reducing sleep depth, and increasing wakefulness.
Sleeping under artificial light long-term is also detrimental to a baby's visual development. Turning off the lights during sleep allows the eyes and ciliary muscles to rest fully. Continuous exposure to light, however, means the eyes and muscles never get adequate rest. This can easily damage the baby's retinal health and hinder normal visual development.
If lights must stay on, use an eye mask
For those genuinely afraid of the dark or unable to sleep in darkness, experts recommend wearing an eye mask at night. Additionally, minimize nighttime awakenings, as these also disrupt melatonin secretion.
Here, "light" refers not just to bright lamps but especially to dim ambient lighting—like nightlights or the glow from a TV left on while napping on the couch late at night. Prolonged exposure to such light during sleep can trigger unhealthy physiological changes.
The downsides of sleeping with the lights on are more numerous than you might imagine!
1. Reduced Sleep Quality
This constitutes light pollution. Prolonged exposure can cause restlessness and anxiety in infants and young children, shortening sleep duration and reducing sleep depth.
2. Impaired Vision
Sleeping with lights on significantly increases the risk of myopia! It disrupts the reticular activating system in children's eyes, potentially damaging the retina and hindering healthy vision development.
A study of 479 myopic patients aged 2-16 found that infants under two sleeping with lights on developed myopia four times more frequently than those in darkness. The brighter the light, the higher the risk.
3. Stunted Growth! Children release growth hormones during sleep. Exposure to light suppresses these hormones, slowing developmental progress.
Why does sleeping make you gain weight?
1. Bedroom brightness affects blood lipids and obesity levels.
Japanese researchers conducted a study. One group slept in dimly lit rooms below 3 lux (a unit of light intensity), while the control group slept in rooms exceeding 3 lux.After a period, the control group gained an average of 4.4 pounds (about 2 kilograms) and had waistlines over 2 centimeters larger.
A 2014 study in the American Journal of Epidemiology found that among 100,000 women, those chronically exposed to light at night had 14% overweight, 25% obese, and 16% with waistlines over 35 inches(approximately 88 cm).
2. Prolonged light exposure increases the proportion of "bad" fat.
As daily "exposure" time increased, the experimental mice gained weight, with total fat mass rising by 57%.
Excessive "exposure" suppressed the formation of brown fat in the mice while promoting the formation of white fat.The former is "good" fat, generating heat and maintaining body temperature; the latter is "bad" fat, contributing to weight gain, obesity, inflammatory responses, and increased heart disease risk.
3. Excessive bedroom brightness at night may also lead to increased food intake.
Bright bedroom lights disrupt the secretion of two key hormones: one is the "satiety hormone," which promotes feelings of fullness and prevents overeating;the other is "ghrelin," which triggers hunger and prompts food seeking.
A 2004 study published in PLOS Medicine revealed that sleep deprivation lowers "satiety hormone" levels while raising "ghrelin" levels, leading to increased food intake and weight gain.
Sleeping with the lights on may signal psychological issues
Sleep with lights on disorder refers to an unhealthy psychological habit where individuals must sleep with lights on at night and cannot turn them off during sleep, creating a dependency on light.
The underlying pathology of this habit is a fear of darkness. This fear often originates in childhood, a period when children are particularly drawn to stories about ghosts and spirits. Such tales frequently unfold against the backdrop of nighttime or darkness, where unseen entities appear to heighten their mystique.
Over time, children associate fear of supernatural beings with darkness itself, developing a dependency on light that prevents them from sleeping with the lights off. This is a primary cause of light-dependent sleep. Additionally, traumatic experiences in dark settings—such as unexpected frightening events or nightmares—that remain unresolved can also cultivate a fear of darkness.
For those with a habit of sleeping with the lights on, it's important to educate them with atheistic principles, explaining that ghosts and monsters do not exist in this world. A gradual approach can also be taken: start by having several people turn off the lights and talk together, then progress to several people sitting quietly in the dark, then two people sleeping together with the lights off, then one person sitting quietly in the dark... finally, one person sleeping with the lights off.
Sleeping in darkness promotes better rest. If you have a habit of sleeping with the lights on, it's best to correct it as soon as possible.
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