Following an irregular sleep and meal schedule over a prolonged period can lead to an increased risk of obesity and diabetes, according to a new study from Brigham and Women’s Hospital and the Division of Sleep Medicine at Harvard Medical School.
Researchers restricted the meal times and sleep schedules of 21 healthy adults, both young and old, over the course of five weeks. For three of those weeks, the participants were exposed to “circadian misalignment,” meaning that the participants were put on a 28-hour day schedule during which they were allowed to sleep for 5.6 hours out of every 24.
Participants lived in the lab for the duration of the study and were monitored closely.
Results showed that participants experienced a decrease in resting metabolic rate and an increase in glucose secretion, and three out of the 21 participants were pre-diabetic by the end of the study. Once participants were allowed to resume normal sleeping and eating habits, they all recovered.
“Your internal 24 clock can’t synchronize to a 28 hour schedule. Most of the time in the week when those participants are sleeping or active, eating or fasting, are times when their bodies are not optimally primed to respond,” said Harvard Medical School professor Orfeu M. Buxton, a lead author on the study titled “Adverse Metabolic Consequences in Humans of Prolonged Sleep Restriction Combined with Circadian Disruption.”
Professor Steven A. Shea, an HMS professor and the paper’s senior author, explained that the study was partially inspired by epidemiological research showing increased rates of diabetes and obesity among shift workers who sleep during the day.
Although the recent findings do not prove conclusively that shift workers are likelier to become diabetic or obese specifically because of their unusual sleep schedules, they do support the data of the epidemiological studies.
“Standing alone based on a month-long experiment in very healthy people, it’s very difficult to extrapolate the results to diabetes, but in the face of all the epidemiological studies showing the adverse metabolic changes associated with shift work, it’s tempting to think about this extrapolation,” said Shea.
“If these findings [...] persist over many months or years, this could well be the reason by which shift workers gain weight and some of them become more prone to diabetes,” he continued.
Buxton explained that college students, like shift workers, often experience circadian disruption, partially due “social jet lag,” which occurs when people stay up late and sleep in on weekends to socialize and then catch up on lost rest.
Computer and cell phone use can also cause sleep disruption, since technological devices emit blue “daytime” light that further confuses circadian rhythms and makes sleeping more difficult.
“Sleep researchers are up against a $100 billion dollar industry that is dependent on college students using cell phones and computers getting this night time blue light that disrupts circadian rhythms,” said Buxton. “I feel like a we’re a little pebble against a tsunami.”
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