The National  Memo Logo

Smart. Sharp. Funny. Fearless.

Monday, December 09, 2019

Skimping On Sleep May Activate The ‘Munchies’

By Kathryn Doyle

(Reuters Health) – Getting too little sleep may activate the same chemical pathways in the brain that are involved in heightened attraction to and enjoyment of junk food associated with marijuana use – also known as “the munchies” – according to a small U.S. study.

Researchers found that a night of restricted sleep was followed by extended peaks, later in the day, in natural signaling chemicals that regulate hunger and pleasure. They think that may be one reason sleep deprivation is linked to weight gain.

“Our current study adds to that growing literature and suggests that along with changes in leptin and ghrelin, alterations in endocannabinoids – all changing in the direction to favor food intake – may be mechanisms by which sleep restriction promotes overeating,” said lead author Erin Hanlon, a research associate in endocrinology, diabetes and metabolism at the University of Chicago.

“And, on a larger scale, evidence from both laboratory and epidemiologic studies have consistently associated insufficient sleep or short sleep with increased risk of obesity,” Hanlon said.

The researchers studied 14 healthy young adults ranging in age from 18 to 30 years who got four nights of sufficient sleep, about eight and a half hours, then four nights of sleep restricted to 4.5 hours. The two sleep tests took place in a sleep lab and were separated by a month.

During waking hours, participants were housed in a private room and kept basically sedentary. They had three identical meals at 9 a.m., 2 p.m. and 7 p.m.

In each test, calorie intake was controlled for the first three days and on the fourth day participants were allowed to eat as much or as little as they liked from a buffet tailored to individual preferences. Meanwhile, researchers monitored participants’ calorie intake and analyzed blood samples.

Participants also answered questions about their hunger, appetite, energy level and mood during the 24-hour period of blood sampling, 25 minutes before each meal and one hour and 35 minutes afterward.

When sleep deprived, participants had higher levels of endocannabinoid 2-arachidonoylglycerol (2-AG), a chemical signal that makes foods, particularly junk foods, pleasurable. This blood chemical is usually low overnight and rises steadily during the day, peaking in the afternoon.

But in the sleep-deprived phase, 2-AG remained elevated late in the evening and participants reported higher hunger scores, according to the results in the journal Sleep.

“These are the first results showing that sleep restriction influences the endocannabinoid system in humans,” said Frank Scheer of the Medical Chronobiology Program at Brigham and Women’s Hospital in Boston who wrote a commentary alongside the new study. “This opens up a new insight into systems involved in energy balance and food reward,” he told Reuters Health by email.

“Previous studies had shown that experimental sleep loss causes an increase in ‘hunger hormone’ ghrelin and a decrease in ‘satiety hormone’ leptin,” Scheer said. “The increase in the peak in endocannabinoids following sleep restriction provides an additional mechanism that could help explain an increase in hunger.”

Adults should aim for seven to nine hours of sleep per night, he said.

“With decreasing amounts of sleep, the metabolic effects appear to become progressively stronger,” Scheer said.

Photo: A shop worker rests in the shade along the beach in Recife June 10, 2014. In a project called ‘On The Sidelines’ Reuters photographers share pictures showing their own quirky and creative view of the 2014 World Cup in Brazil. REUTERS/Brian Snyder

Researchers With Opposing Views On Salt Intake Are Ignoring Each Other

By Kathryn Doyle

(Reuters Health) – On the question of whether the population would benefit if people cut back on salt, researchers fall into two camps, according to a new report.

While most studies have concluded that cutting salt would have benefits, about a third do not agree. And researchers on both sides of the issue tend not to take the other side’s findings into consideration.

“We have not analyzed why there is a divide, we can only suggest or make assumptions after the fact,” said Ludovic Trinquart, the lead author of the new report and a Columbia University Epidemiology Merit Fellow at the Mailman School of Public Health in New York City.

Trinquart and colleagues reviewed 269 primary studies, analyses, clinical guidelines, consensus statements, comments and letters on salt intake and health published between 1979 and 2014. They sorted the papers based on whether or not they supported the link between reduced sodium intake and lower rates of heart disease, stroke, and death.

They found that 54 percent of papers supported the hypothesis, 33 percent refuted it, and 13 percent were inconclusive.

Those that supported the hypothesis tended to cite other papers that supported it, too, while those that refuted tended to cite others that refuted also, with little crossover between the camps.

As reported in the International Journal of Epidemiology, Trinquart’s team found 10 systematic reviews that pooled the data from a total of 48 primary studies – but each review did not necessarily include all available studies. Choosing which primary studies to cite influenced the conclusion of systematic reviews, the authors found.

“One side preferentially cites previous papers that found a similar conclusion,” Trinquart told Reuters Health by phone.

His own study cannot offer any individual or population-level advice on actual salt intake, he said.

“On the one side, there is strong bias by the salt industry,” said John P.A. Ioannidis of the Stanford Prevention Research Center, who wrote a commentary on the study. “On the other side, there is also bias from academics who want to defend their theories.”

There is consensus that salt intake needs to be reduced, but by how much is still up for debate, Ioannidis told Reuters Health by email.

“I am a proponent of the idea that salt is bad for you,” said Bruce Neal of the George Institute for Global Health in Sydney, Australia, who wrote another of the three commentaries accompanying the study. “Almost everyone is eating more than they actually require.”

We can learn more from considering study quality instead of just sorting all studies into two camps, Neal told Reuters Health by phone.

“A lot of the debate is around weak research,” he said.

National and international guidelines from institutions like the World Health Organization unanimously recommend salt reduction, he said.

“We lack a large definitive randomized trial that shows that reduced salt protects against heart attack, but there is very little evidence that reduced salt would do harm,” Neal said.

Today adults consume an average of 10 grams of salt per day, but any more than two grams a day and the kidneys “are just trying to pee out as much salt as they can,” he said.

“There’s very good evidence that if you eat too much salt it pushes up your blood pressure,” he said.

Studies that refute this hypothesis divide people by how much salt they are already eating, but people who eat very little salt may have already had a heart attack or stroke or may have terminal stage cancer, so their worse health outcomes have other underlying causes, he said.

“The vast majority of those who work in clinical medicine say it is much more likely that salt is bad for you than good for you,” Neal said.

SOURCE: International Journal of Epidemiology, online February 17, 2016.

Photo: A new menu from Applebee’s restaurant is seen at one of its outlet in the Manhattan borough of New York City November 30, 2015. A tiny salt shaker symbol that warns certain meals are high in sodium will appear on menus in chain restaurants in New York City, the first U.S. city to take the step in an effort to combat heart disease and stroke. REUTERS/Brendan McDermid

For Fitness Motivation, Losing Money Beats Earning More

When employers are trying to encourage workers to get more physical activity, offering a monetary award that can be lost if the goal is not met yields better results than offering a bonus that can be gained if the goal is met, according to a new study.

“Most people assume that people are rational, but we know that this is not true. People are irrational but in predictable ways,” said lead author Dr. Mitesh S. Patel of the Perelman School of Medicine at the University of Pennsylvania in Philadelphia.

Patel’s group studied 281 overweight or obese adult employees who enrolled online. Participants reported their height and weight, and used a smartphone step-counter app to track their activity levels for 13 weeks.

On average, U.S. adults take about 5,000 steps per day. For this study, participants were given a goal of at least 7,000 steps per day and then randomly divided into four groups. One group received no incentives, another received $1.40 for each day they met the goal, another lost $1.40 from a monthly incentive ($42) each time the daily goal was not met, and the last group drew lottery numbers for a chance to win $50 which they could only collect if they had achieved 7,000 steps on the previous day.

All received daily feedback on their step count.

The loss-incentive group met their step goal on 45 percent of days, compared to 36 percent of days in the lottery group and 35 percent in the gain incentive group. Those in the comparison group with no incentive only met their goal on average 30 percent of days, the researchers reported in the Annals of Internal Medicine.

During the following weeks, when step count was still reported but no incentive was offered, step counts decreased for all groups.

“According to a few seminal behavioral economics experiments, people don’t like losing something twice as much as they like gaining the same thing, as a rule of thumb,” said Marc Mitchell of the University of Toronto, who was not part of the new study.

A more tailored design might have yielded different results – like if the researchers had measured how much each person was walking before the study and asked them to increase their step count by 2,000, rather than setting the same goal for everyone, Mitchell told Reuters Health by email.

“Just tracking activity using a smartphone or wearable device will help, but for those who are overweight or obese or have a chronic condition tracking alone is unlikely to boost activity,” which is where a financial incentive comes in, Patel said.

“About 80 percent of employers in the U.S. use financial incentives of some kind in wellness programs,” he said.

Most simply lower insurance premiums if employees achieve health and wellness goals, he noted.

Many are moving to more penalty based schemes given the short-term financial benefit for the company, but this may not be a good way of promoting quality health behavior change, Mitchell said.

“For most employer wellness programs around the country, you do something, you get paid for it,” Patel told Reuters Health by phone. “Sometimes relatively soon, sometimes off into the future.”

In this case, the gain and loss incentives were the same, only framed differently depending on the group, he said.

This technique of framing the incentive comes from previous work in behavioral economics, Patel said.

He added, “I think the evidence is clear, these financial incentives could be better designed if they were based on insights from behavioral economics.”

SOURCE: Annals of Internal Medicine, online February 15, 2016.

(This version of the story has been refiled to fix typos in paragraphs one and two)