WSJournal. Sleep's Surprising Effects on Hunger
Getting too little sleep often makes people feel hungrier than normal, leading to overeating and weight gain. A study in the journal Sleep found a biological reason for this that surprised the researchers.
Lack of sleep triggers hormonal changes, but the hormones affected are different for men and women, the study found. The researchers said they expected sleep deprivation to affect glucose or insulin levels in both sexes.
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Mark Brewer
Lack of sleep affected different hormones in men and women.
Thirty normal-weight men and women in their mid-30s participated in two inpatient stays at an obesity research center in New York City. Each stay was six days long and involved five overnight sleeps.
Participants slept four hours a night during one stay and seven hours a night in the other, with a three-week break in between. Daytime napping wasn't allowed. During both stays, subjects ate a calorie-controlled diet for the first four days and had unlimited access to food on the fifth and sixth days. Blood samples were analyzed daily for seven hormones that influence appetite and food intake: glucose, insulin, leptin, ghrelin, adiponectin, total glucagon-like peptide 1 (GLP-1) and peptide YY3-36.
Abbreviated sleep had no effect in either sex on glucose, insulin, leptin, adiponectin and peptide YY3-36, compared with hormone measures after normal sleep, results showed. But levels of ghrelin, which stimulates hunger, were elevated only in the men after the short periods of sleep.
Meanwhile, levels of GLP-1, an appetite-suppressing hormone, were lower in women after the short periods of sleep but were unchanged in men. All participants consumed about 300 more calories on the fifth day after shortened sleep than after long sleep. The study suggests that lack of sleep may result in enhanced appetite in men. But in women, sleeping too little results in feeling less full.
Caveat: The stress hormone cortisol wasn't measured and may have been affected by reduced sleep, researchers said. Participants lost about two pounds during the study, which surprised researchers and may have affected hormone levels, they said. It isn't known if similar hormone changes would occur in overweight people.
Short Sleep Duration, Glucose Dysregulation and Hormonal Regulation of Appetite in Men and Women
Umbilical benefits: A 45-second delay in cutting the umbilical cord following a preterm birth significantly improved body temperature, blood oxygen and other indicators of health in newborns compared with clamping the cord immediately after birth, according to a report in Advances in Neonatal Care.
Waiting to clamp the umbilical cord had benefits for the health of premature newborns.
Most U.S. hospitals cut or clamp the umbilical cord seconds after a birth, but research shows waiting up to a minute or more before clamping gives newborns a rich infusion of stem cells and increases blood volume.
The study compared early and delayed clamping in 349 premature infants born at a northern Alberta, Canada, hospital from 2008 to 2009. The umbilical cord was cut 45 seconds after delivery in 236 births and immediately after delivery in 113 births, which served as a control group. On average, the infants were born at 29 weeks gestation and weighed 3.3 pounds.
Infants in the delayed-clamping group had significantly higher hemoglobin levels than control babies and they required fewer hospital admissions for low-body temperature: 19.5% compared with 31%. Necrotizing enterocolitis, an intestinal condition related to prematurity, occurred in 1.3% of the delayed-clamping group and 5.4% of controls. Blood-pressure support was required in 8.1% and 12.4% of the delayed-clamping and control groups, respectively.
While the study was in progress, the Society of Obstetricians and Gynecologists of Canada published guidelines that recommended 60 seconds of delayed clamping in all preterm births. The World Health Organization supports delaying cord clamping, regardless of gestational age or fetal weight, until the umbilical cord is flat or approximately three minutes or more after birth. The American College of Obstetricians and Gynecologists said in November that the ideal time for cord clamping hasn't been established, a position endorsed by the American Academy of Pediatrics.
Caveat: The delayed-clamping group had lower scores on the five-minute Apgar newborn-vitality test compared with controls, but the difference wasn't clinically significant, researchers said.
Flavonoids and flu: Two plant-based flavonoids—disease-fighting compounds found in many foods—significantly impaired the infectious activity of H5N1 avian-flu virus in laboratory experiments and may form the basis of future influenza treatments, a report in Antiviral Research says. H5N1 flu hasn't been reported in the U.S., but the virus has infected more than 600 people in other countries and appears to be resistant to traditional anti-viral treatments, researchers said.
Experiments in Germany tested 22 flavonoids on human lung cells infected with the H5N1 influenza A virus. Six of the 22 exhibited potent anti-viral properties and two—baicalein and biochanin A—were singled out for their performance. Baicalein is used in traditional Chinese medicine and biochanin A is found in peanuts, chickpeas and other legumes. In separate experiments, the two flavonoids were added to lung-cell cultures before, during and after infection with H5N1, and tested on H5N1-infected cells treated with zanamivir (brand name Relenza), an antiviral drug prescribed to flu patients.
Both baicalein and biochanin A interfered with critical steps in the virus's natural replication cycle, the study found. The flavonoids inhibited the secretion of various inflammatory cells called cytokines in H5N1-infected cells, but had no effect on noninfected cells or tumor necrosis factor, a key inflammatory protein. The effects were most pronounced after 48 hours, the study found. Baicalein and biochanin A also enhanced the anti-viral effects of zanamivir in cell cultures.
Although structurally similar, the flavonoids differed in their anti-influenza mechanisms, researchers said. More studies are needed to decipher the pharmacological actions of flavonoids, they said.
Caveat: Baicalein and biochanin A haven't been tested on animals or human subjects infected with H5N1.
Analgesic exercise: Patients who got out of bed and walked on the morning after knee-replacement surgery had significantly less knee pain after the walks than before the walks, according to a pilot study in Acta Anaesthesiologica Scandinavica. The analgesic effects of exercise have been studied in various pain conditions, but fear of pain may limit patient exercise immediately after surgery, when pain is most acute, researchers said.
The subjects were 30 men and women who underwent knee arthroplasty at a Copenhagen hospital from 2009 to 2010. On the first post-operative morning, they walked a distance of 82 feet twice using a walking frame, with a 20-minute rest between walks. Pain assessments were taken at rest, with hips and knees flexed, before each walk, after walking 20 feet and 82 feet, and 5 and 20 minutes post-walk. Patients scored their pain from 0 (no pain) to 100 (worst pain). Pressure probes applied near the surgical site tested pain threshold or pain awareness; pain tolerance—the point of unbearable pain—was measured with finger electrodes.
Pain was significantly reduced for all assessments at 5 and 20 minutes after the second walk compared with the first, results showed. Pain reduction on the second walk occurred after patients had walked 20 feet. Subjects' pain threshold, but not pain tolerance, was significantly increased post-walk compared with pre-walk. Exercise may trigger naturally occurring opioid and non-opioid compounds that affect the nervous and musculoskeletal systems, researchers said.
Caveat: Patients received pain medications before and after surgery that would have taken effect before the pain assessments and the two walks, researchers said. The study didn't include a control group.
Perceived stress: Feelings of being overloaded and stressed by the demands of daily living can increase a person's risk of developing heart disease, a meta-analysis in the American Journal of Cardiology suggests. The link between stress and poor heart health is well known, but most research has focused on hours of work and psychological factors.
Researchers at Columbia University pooled the results of six studies in five countries that examined the long-term effects of perceived stress in 118,696 men and women, who were in their mid-50s at the time. The studies, conducted from 1991 to 2006, tracked the heart health of participants over approximately 14 years. Two studies used validated scales of perceived stress, which evaluated the degree to which the subjects regarded life as unpredictable or uncontrollable, and four included questions about the frequency and nature of stressful experiences. All studies considered traditional cardiac risk factors, such as smoking and hypertension.
Subjects who perceived themselves as highly stressed had a 27% increased risk of angina or heart disease, heart-related hospitalization, and cardiac death than those who didn't report feeling stressed, the analysis showed. Researchers compared the increased risk to smoking an additional five cigarettes a day and significant increases in cholesterol and blood pressure. Chronic stress may increase activity in a feedback loop called the hypothalamic pituitary axis, which regulates many body processes, they said.
Caveat: Stress was self-reported by subjects. Most studies didn't adjust for depression and anxiety, which are associated with perceived stress and cardiovascular disease, researchers said.
Meta-Analysis of Perceived Stress and Its Association With Incident Coronary Heart Disease
Wedding weight: Nearly two-thirds of engaged men want to lose weight for their wedding day, especially if the ceremony is expected to be quasiformal with at least 150 guests, a study in the journal Appetite says. Weight loss, exercise, tanning, and teeth whitening are common pre-wedding practices among U.S. brides-to-be, but it isn't clear how prospective grooms manage their weight and shape.
Cornell University researchers surveyed 163 men ages 19 to 30 when they were six months away from their weddings in 2006. About half were college graduates. Self-reported height and weight indicated that 46% were overweight, 31% had a normal weight and 23% were obese. Subjects were asked about their ideal wedding weight, the methods used to change their weight, details of the ceremony and their involvement in the planning.
Results showed that 64% of men wanted to weigh about 20 pounds less on their wedding day, though only 39% actively tried to lose, and 12% wanted to weigh about 13 pounds more. Twenty-four percent reported being happy with their weight. To lose weight, men ate more fruits and vegetables, drank more water and consumed less food. About 20% reported skipping meals and less than 10% took diet pills or fasted. To gain weight, men ate and exercised more. About 4% took up smoking to prevent weight gain.
Caveat: The study lacked a comparison group of men who weren't engaged and didn't include gay men, whose views on wedding weight and appearance may be different than heterosexual men, researchers said.
