Mid-afternoon slump? Why a sugar rush may not be the answer

Protein -- not sugar -- stimulates cells keeping us thin and awake, a new study suggests.

A new study has found that protein and not sugar activates the cells responsible for keeping us awake and burning calories. The research, published in the Nov. 17 issue of the scientific journal Neuron, has implications for understanding obesity and sleep disorders.

Wakefulness and energy expenditure rely on "orexin cells," which secrete a stimulant called orexin/hypocretin in the brain. Reduced activity in these unique cells results in narcolepsy and has been linked to weight gain.

Scientists at the University of Cambridge compared actions of different nutrients on orexin cells. They found that amino acids -- nutrients found in proteins such as egg whites -- stimulate orexin neurons much more than other nutrients.

"Sleep patterns, health, and body weight are intertwined. Shift work, as well as poor diet, can lead to obesity," said lead researcher Dr Denis Burdakov of the Department of Pharmacology and Institute of Metabolic Science. "Electrical impulses emitted by orexin cells stimulate wakefulness and tell the body to burn calories. We wondered whether dietary nutrients alter those impulses."

To explore this, the scientists highlighted the orexin cells (which are scarce and difficult to find) with genetically targeted fluorescence in mouse brains. They then introduced different nutrients, such as amino acid mixtures similar to egg whites, while tracking orexin cell impulses.

They discovered that amino acids stimulate orexin cells. Previous work by the group found that glucose blocks orexin cells (which was cited as a reason for after-meal sleepiness), and so the researchers also looked at interactions between sugar and protein. They found that amino acids stop glucose from blocking orexin cells (in other words, protein negated the effects of sugar on the cells).

These findings may shed light on previously unexplained observations showing that protein meals can make people feel less calm and more alert than carbohydrate meals.

"What is exciting is to have a rational way to 'tune' select brain cells to be more or less active by deciding what food to eat," Dr Burdakov said. "Not all brain cells are simply turned on by all nutrients, dietary composition is critical.

"To combat obesity and insomnia in today's society, we need more information on how diet affects sleep and appetite cells. For now, research suggests that if you have a choice between jam on toast, or egg whites on toast, go for the latter! Even though the two may contain the same number of calories, having a bit of protein will tell the body to burn more calories out of those consumed."

Finding sleep's sweet spot Study connects early bedtime and 'adequate' sleep with heart healthy choices

April 21, 2016
Science Daily/University of Delaware
A new study shows that when it comes to promoting healthy hearts, it's not a matter of getting more sleep. It's a matter of getting adequate sleep at optimal times, say researchers.

Night owls should take special note of a new study by University of Delaware researcher Freda Patterson and collaborators at the University of Pennsylvania, Drexel University and the University of Arizona College of Medicine, who found that the early-to-bed, early-to-rise approach aligns much better with cardiovascular health.

Sleep deficits and poor-quality sleep have been linked to obesity and a myriad of health problems, but this study shows that when it comes to promoting healthy hearts, it's not a matter of getting more sleep. It's a matter of getting adequate sleep at optimal times.

Doing that seems to reduce the kind of behaviors -- smoking, sedentary lifestyles and poor dietary choices -- that put hearts in harm's way.

"There are some who believe that sleep as a physiological function is upstream to these heart-health behaviors," said Patterson, assistant professor of behavioral health and nutrition in the University's College of Health Sciences. "If that is true, the implication would be that if we can modify sleep as a central risk factor, we might be in much better position to leverage or modify some of our most stubborn cardiovascular risk behaviors such as tobacco use."

The study, published in the Annals of Behavioral Medicine, examined the duration and approximate timing of sleep to see what patterns might be linked to the three prime suspects of cardiovascular trouble -- smoking, poor diet and sedentary habits. Those three behaviors have been blamed for about 40 percent of cardiovascular deaths in the United States and the United Kingdom.

The study had an enormous pool of data with which to work, drawing from the United Kingdom's Biobank Resource and a sample of 439,933 adults, between the ages of 40-69.

They found several strong connections, but first, a few notes about definitions and methods.

The study defined short sleep as less than six hours, adequate sleep as seven to eight hours, and long sleep as nine hours or more. Respondents were categorized by their self-reported sleep-timing or "chronotype" -- whether they considered themselves a morning person, more morning than evening, more evening than morning, or an evening person.

Participants were asked about their physical activity, how much time they spent using a computer or watching TV on an average day, how many servings of fruits and vegetables they had each day and how many cigarettes they typically smoked in an average day.

And the bottom line was this -- those whose sleep was either short or long and the night owls who went to bed later were more likely than adequate sleepers and those who went to bed earlier to smoke, remain sedentary and eat fewer fruits and vegetables.

"These data suggest that it's not just sleep deprivation that relates to cardiovascular risk behaviors, but too much sleep can relate as well," Patterson said. "Oftentimes, health messages say we need to get more sleep, but this may be too simplistic. Going to bed earlier and getting adequate sleep was associated with better heart health behaviors."

The American Health Association reports that only 5-10 percent of adults meet ideal standards in diet, physical activity and tobacco use. The rest of us have work to do.

"We know that people who are active tend to have better sleep patterns, and we also know that people who do not get their sleep are less likely to be active," Patterson said. "A pressing question for practitioners and researchers is how do you leverage one to improve the other?"

Data on the population studied were derived from the United Kingdom Biobank Resource, which draws on the UK's national health service. Subjects were between 40-69 years old during the four-year data collection period, which went from 2006-10.

Despite the enormous sample size, the data had some limitations, Patterson said. Population diversity was limited, for example. Ninety-five percent of respondents were white. And the data were largely based on self-report.

Further study is required to determine whether promoting adequate sleep and earlier-to-bed patterns would improve heart health.

http://www.sciencedaily.com/releases/2014/11/141103121020.htm