Light — Not Always Enlightening

The best scientists make connections between work and life. Rebecca Boyle wrote,

Randy Nelson, a circadian biologist at Ohio State University, has been studying light’s effects on depression and obesity since 2004, when one of his graduate students was hospitalized for a staph infection. The student complained bitterly about the bright lights in his room and in the hospital hallway, which robbed him of sleep and stressed him out.

Back at the lab, Nelson and grad student Laura Fonken brought in special rodents, and kept the lighting in their quarters relentlessly bright, like a maximum-security prison. The subjects became listless and depressed, with glitches in their learning abilities and memory, and they even lost their taste for sugar-water treats.

Then the researchers tried providing only a little bit of night illumination in the rat barracks — what in human terms would be the equivalent of leaving a computer or TV screen on in the bedroom. They got the same result — mopey rodents who were definitely not at the top of their game. Apparently, low-quality sleep affects organisms like low-quality food. It can keep a creature alive and functioning, but it is not capital-L Life.

And now the bad news

Also, the experimental animals got fat, and here is the scary part: “They were eating the same number of calories as their dark-sequestered mates.” What was going on? The answer Nelson and Fonken came up with was that light-activated messenger RNA molecules go around switching genes off and on, and this regulates circadian rhythms.

Messing with the process comes with a price tag. Without knowing every last detail, they concluded that the link could not be doubted. Just like malnourishment, sleep interference can, and will, find a way to forge an inevitable path toward obesity.

Melatonin

Epidemiologist Richard Stevens of the University of Connecticut explained to journalist Boyle the actions of the hormone melatonin, which lowers the body’s core temperature and induces drowsiness. In animals with backbones, from fish to humans, melatonin regulates the sleep-wake cycle and calibrates the metabolism. Stevens explained,

Production of melatonin should begin at dusk, when we are supposed to sleep. Light — not wakefulness itself, but light — shuts it off.

Over the next few years, some research here and there continued to link nocturnal artificial light with an increased risk of weight gain. It was hard to prove the particulars of causation. In 2019 a study showed that, for women middle-aged and above, illumination in the hours of darkness was paired with a higher likelihood of obesity. As it turns out, the light does not even need to be as bright or concentrated as a device’s screen. Apparently, damage can be done by seepage through and around curtains, and by clocks that glow in the dark.

A study led by Dr. Yong-Moon Park involved “almost 44,000 generally healthy women, ages 35 to 74.” What happened?

Many — about 17,000 — slept with a nightlight in the room, while more than 13,000 left a light on outside the bedroom and about 5,000 slept with a television or light on in the bedroom.

After almost six years of follow-up, women who slept with a television or light on in the room were 22 percent more likely to be overweight and 33 percent more likely to be obese than women who slept in total darkness without even a nightlight or the glow from an alarm clock.

Whether or not the subjects had “enough” hours of sleep, what made the difference was the artificial light during sleep time.

Your responses and feedback are welcome!

Source: “The End of Night,” Aeon.co, 04/01/14
Source: “Sleeping with lights or TV on tied to obesity,” Reuters.com, 06/10/19
Image by Evan/CC BY-ND 2.0

The Assault of Light and Sound

This blog has been tracing the progress of awareness about how detrimental television is. Back in 2011, Rose Eveleth wrote for Scientific American,

Television watching […] turns out to be a better predictor of bad eating habits than does parental weight, race and income, and a child’s gender and ethnicity — together…

One study published in the Archives of Pediatrics & Adolescent Medicine in 2006 estimated that for every hour of daily television, kids consumed an additional 167 calories.

With TV, it’s not just the sheer noise or the disturbing subject matter or the commercials for sugar-sweetened beverages and junk food that lead by a circuitous route, one way or another, to childhood obesity. Interference with sleep is now recognized as one of the screen-viewing side effects that blends with snacking and prolonged sitting. Another problem is the light itself, which spills from the screen.

In 2013, it came to the attention of researchers that children and adolescents were spending an average of almost eight hours per day staring at screened devices. A study of 1,803 teens revealed that the ones who spent more time with computers, TVs, video gaming setups, tablets, and cell phones were more likely to develop metabolic problems. They had dicey bloodwork and bigger waistlines.

Krysteena Stephens, M.A., IMFT, and Victoria Dunckley, M.D., reported that watching TV during meals has an undesirable effect because, for some reason, kids who do that eat less nutritious foods. This next example is rather heartrending because it concerns little children who were two, three, and four years old. The parents reported that…

[…] children who watched more television on average were twice as likely to consume soft drinks or other sweetened beverages every week. The article also reported a 50 percent increase in soft drink consumption for every additional hour of television the child watched.

If parents can’t change that situation, who can? One of the sticking points is that parents can’t even control their own lousy habits, and as the authors state, “Parental role modeling plays a predominant role in the health and weight of a child.” They go on to say,

Not surprisingly, parents who engage in higher levels of screen-time and sedentary behavior also have children who engage in more screen-related activities and sedentary behavior.

They mention another study which reported that, when preschool children watch two or more hours of TV each day, they are more likely to be overweight than the ones who don’t, and it messes with their ability to do things in the world:

Since self-discipline, motivation, and impulse control depend on executive functioning, indirect effects from screen-time may include dysregulated eating habits, being out-of-tune with bodily hunger and fullness cues, and lack of motivation to direct one’s energy physically.

Artificial light affects every aspect of the environment. A lot can be said about the carnage to nocturnal animals and migratory birds, any creature whose internal clock depends on melatonin. For humans, it seriously pulls the melatonin levels down. Our bodies mistake blue light for natural daylight, and people’s insomnia and overall tiredness are worsened even when they only peek at their phones during the night less than once a week — a pretty extreme reaction for such a small transgression.

Journalist Rebecca Boyle summed it up in a 2014 article:

A growing body of evidence shows that light pollution exacerbates, and might directly cause, cancer, obesity, and depression, the troublesome triumvirate of industrialised society.

Your responses and feedback are welcome!

Source: “Hidden Drivers of Childhood Obesity Operate Behind the Scenes,” ScientificAmerican.com, 10/13/11
Source: “An Overlooked Factor in the Childhood Obesity Epidemic,” PsychologyToday.com, 12/23/13
Source: “The End of Night,” Aeon.co, 04/01/14
Image by Ken Savage/CC BY-ND 2.0

Does Light Make Us Heavy?

A very comprehensive 2010 article by Angela Spivey, published in the journal Environmental Health Perspectives, traced the history of the idea that interrupted sleep makes it easier for the body to store fat and harder to eliminate it. Research published in 2006 revealed that “women who reported sleeping 5 or fewer hours per night were at greater risk for weight gain and in general weighed more compared with women who slept 7-8 hours per night.”

Three years later, the publication Obesity Reviews devoted an entire special issue to the role played by circadian biology in the body’s metabolism and especially in the advent of obesity. It pointed out how some studies indicate that the total amount of sleep may not be the major factor, but rather the amount of time spent in the different stages of sleep — known as a person’s sleep architecture. In the same year, others used the science of polysomnography to discover that men who got less slow-wave sleep (the deepest stage) were more prone to obesity.

Are we dumber than plants?

Part of the lore of home-based cannabis grow-rooms is that the plants’ night must not be interrupted by light for even a second. Yet humans habitually expose ourselves to light and activity (and food) at the times when every cell and organ inside our bodies expect quiet, dark, and sleep.

Studies in the areas of both sleep and epidemiology show that insufficient, interrupted, and randomly scheduled sleep is an independent risk factor for weight gain and other metabolic disorders. Metabolic syndrome, Spivey notes, includes “a variety of symptoms that can lead to heart disease, stroke, or diabetes, including high triglycerides and cholesterol, hypertension, insulin resistance, and glucose intolerance.”

The message is difficult to convey to the public because scientists are still not exactly sure how it all works. When genetic factors are involved, the picture becomes even more complicated. But even though all the connecting dots have not yet been pinpointed, the connection cannot be ignored or denied. According to the study:

When most people speak of the circadian clock, they think of the central clock in the brain, located in the suprachiasmatic nucleus of the hypothalamus. But over the last 20 years, scientists have learned that almost all cell types — including fat cells, heart cells, and liver cells — have clock mechanisms, too.

[T]hese peripheral clocks can be entrained by (that is, changed to align with) environmental cues other than light, such as eating and activity. Moreover, exposure to these cues at times when they aren’t “expected” by the body may lead to obesity and related health effects.

Spivey’s article, “Lose Sleep, Gain Weight: Another Piece of the Obesity Puzzle,” describes the highlights of very many important studies that built up this body of knowledge, and includes sophisticated graphics.

A fascinating watch

“The City Dark” is a documentary film released a decade ago that Dr. Pretlow found powerfully interesting, saying, “It looks at how pervasive light pollution is in our modern life and how it is messing with nature and our ‘human’ sense of self.” Night-shift workers are twice as likely to develop breast cancer as day-shift workers, and apparently, light pollution is the connective tissue.

Could there be an obesity connection? Dr. Pretlow wondered at the time if shifts in light could negatively influence eating behavior, and even somehow promote addiction.

Your responses and feedback are welcome!

Source: “Lose Sleep, Gain Weight: Another Piece of the Obesity Puzzle,” NIH.gov, January 2010
Image by Brett Wood/CC BY-SA 2.0

Is Assortative Mating an Obesity Villain?

In 2007, the Rowett Research Institute and the University of Aberdeen wrote about how people tend to become romantically involved with others who have similar characteristics:

For instance, tall people tend to marry other tall people, and we tend to marry within our own social class, within our own educational class, and within our own race.

A doubter might object that, if this were so, the commercial services that report on genetic ancestry would have little reason to exist. At any rate, this is the doctrine of assortative mating. The point of the referenced article was that people also tend to choose partners with “similar body fatness,” and that this might contribute to the obesity epidemic. Their children inherit whatever genes might be responsible for inappropriate weight gain, as well as a collection of attitudes, beliefs, and customs connected with food.

That assortative mating applies to body fat had already been established through BMI measurements, but now it was confirmed with “a sophisticated technique called dual-energy X-ray absorptiometry,” much more accurate and reliable.

But unlike many other factors suggested as obesity villains, assortative mating has increased rapidly and recently. One of the researchers, Professor John Speakman, theorized that people used to marry younger, when it was too soon to tell if a wife or husband would eventually expand.

But now, people go ahead and manifest their body fat destiny much earlier in life. Not only that, but they marry later, when their true obesity status is more likely to have already been revealed, so it is easier to find a prospective mate in the same obesity bracket. Although the idea seems rather tenuous, there may be something to it.

As we discussed previously, a school of thought then arose, holding that…

[…] common environmental influences may play a more significant role in the resemblance of spousal behaviors than assortative mating.

It was also found that using a method other than BMI to measure body fat gave more accurate results on which to base speculations about assortative mating. But a decade later, The Obesity Society publicized a study that used BMI measurement to establish the degree of overweight experienced by almost 900 multinational participants, who were then asked to rate the attractiveness of potential partners by looking at their photos.

The study authors took a long-winded route to explain that the reactions were, figuratively, all over the map, which struck rather a blow to the assortative mating paradigm. The lead author, Professor John Speakman said,

What is new here is that with a large international sample, we can pretty much eliminate the mutual attraction idea as an explanation. Despite the overall patterns, some people prefer individuals of intermediate adiposity and others prefer partners that have obesity over individuals that are lean. However, these preferences were not related to the rater’s own BMI.

Your responses and feedback are welcome!

Source: “Love At First Sight Of Your Body Fat,” ScienceDaily.com, 08/13/07
Source: “Entry into Romantic Partnership is Associated with Obesity,” NIH.gov, 04/09/09
Source: “Does Mutual Attraction Explain Assortative Mating for Obesity?,” GlobeNewsWire.com, 02/21/18
Image by Stuart Richards/CC BY-ND 2.0

Coupling Up? Think Twice.

Many factors have been proposed as being at least partially responsible for obesity. But the idea that starting a romance makes people fat is totally counter-intuitive. “Huh?” you might say. Isn’t early-stage love the time when a person is most careful to keep everything dusted off, polished up, and shipshape? But the headline says, “Entry into Romantic Partnership is Associated with Obesity.”

How can this be? Apparently, it is a pretty well-known fact that established couples, as the years go by, tend to become approximately the same shape. Generally, both are noticeably fit, or both are on the high side of average weight, or both are obese. As authors Natalie The and Penny Gordon-Larsen put it, “Body mass index is highly correlated between spouses.”

But isn’t this page about obesity in childhood? Yes, and it connects with many other posts that delineate exactly how strong parental influence is. Sooner or later, couples tend to produce children and to serve as authority figures and role models, influencing every aspect of those children’s lives, including their weight and general health. How the kids turn out will reflect this upbringing. As the authors say,

The observed concordance of obesity could increase the likelihood that romantic partners may together pass on high-risk behaviors to their offspring.

Consequently, attention to and prevention of adult obesity can prevent a certain amount of child obesity.

Growing together

Whether because of identical habits or shared microbial populations, married couples come to resemble each other, and usually that means the skinnier one gets bigger. Or, to quote the authors again, there are “underlying mechanisms by which the development of obesity in one individual increases the risk of obesity in his/her spouse.”

This explains why initiating a romance is deemed to be an obesogenic event, because if the couple started out different, one of them will eventually come to resemble the other in terms of size and stored fat, or so the theory goes. Are the development of a romantic partnership and the length of cohabitation related to “incident obesity and obesity-promoting behaviors”?

A lot of details are involved, according to this paper. For one thing, the information the researchers worked with came mainly from couples who had not been cohabiting or married for very long, and there is a honeymoon effect in relationships. Inevitably, sooner or later, reality sets in and it’s “trouble in paradise” time.

The nitty-gritty

There are interesting nuances around cohabitation. A woman’s tendency to gain weight kicks in before even a year has passed. For men to start beefing up, takes a bit longer — between one and two years. After more than two years of living together, “concordance” increases even more, especially if the bond has been officiated.

But why do women balloon up so quickly? Possibly, there is an increase in food-intensive social events — meeting each other’s families, bachelorette parties, wedding-cake tasting sessions, and whatnot. Maybe relatives urge them to overeat, thinking that extra nutrition will inspire pregnancy and bring forth grandchildren.

Whether the two are dating, cohabiting, or married, physical activity seems to decrease. This is attributed to a “decline in desire to maintain weight for the purpose of attracting a mate.” For a woman to “let herself go” means she trusts the guy; while he may be thinking, “Hey, her 34-inch waist is a deal-breaker.”

Even an extensive study will have reasons to avoid the making of sweeping generalizations. Obese women may be less likely to marry in the first place, the researchers suggest; and in this particular dataset, only heterosexual couples were surveyed. The researchers quite frankly state,

Our results conflict with other work conducted in racially/ethnically homogenous populations and among older adults…

Childhood Obesity News has been looking at the various purported causes of obesity, and aside from the “usual suspects” there are a lot of alleged obesity villains on the loose in the world. Continuing with the romantic relationship theme, the next topic will be assortative mating.

Your responses and feedback are welcome!

Source: “Entry into Romantic Partnership is Associated with Obesity,” NIH.gov, 04/09/09
Image by Sandra Cohen-Rose/CC BY 2.0