MINNEAPOLIS – Teens who do not sleep enough may be at risk for gaining weight and increased insulin resistance.
That’s the conclusion of a small pilot study conducted by Dr. Dorit Koren and her colleagues at the University of Chicago.
There is already considerable epidemiologic data that lack of sleep is a risk factor for obesity in children and young adults, said Dr. Koren who is with the departments of pediatrics and medicine in the pediatric endocrinology department at the University of Chicago.
There have been studies examining the risk of type 2 diabetes with sleep deprivation in adults, but there has been no population-based data in children examining the risk of type 2 diabetes in children and adolescents – and that’s important because they are not just small adults, she said.
Adolescents tend to be more insulin resistant because of the pubertal growth spurt, and they have a different sleep architecture than do adults, as they tend to be late to bed and late to rise, said Dr. Koren.
Previous studies looking at glucose homeostasis in adolescents have mostly looked at fasting rather than dynamic measures of glucose homeostasis and that is a limitation because fasting measures reflect primarily hepatic insulin sensitivity, she said. Most studies also were conducted in a sleep lab, which is not a natural environment.
She and her colleagues wanted to study adolescents at home and also gauge postprandial glucose metabolism. They enrolled 10 adolescents, aged 13-18 years. A total of 70% were black and 30% were non-Hispanic white. Just under half were male. They were mostly overweight, as measured by body mass index, although some were very lean, and some were very obese, said Dr. Koren.
The patients were first given an overnight polysomnogram, and then told to measure sleep at home through an actigraphy device, and sleep diaries. The actigraphy helped back up the diaries, which are known to be "remarkably inaccurate" among adolescents, said Dr. Koren. They kept track of their sleep for 2 weeks.
The teens then returned for a second visit to the clinic. The researchers analyzed the average bedtime and waking time, and then asked them to restrict their sleep by going to bed an hour later. After returning again, the new measures after sleep restriction were compared with the earlier measures.
There was a strong correlation between weight and sleep duration, with longer sleep associated with less weight. They also saw a trend toward a greater waist circumference in adolescents who slept less.
There was a significant negative association between sleep duration and the 90-minute oral glucose tolerance test, with a P = .036. Restricted sleep also led to greater insulin resistance as measured by the homeostasis model assessment of insulin resistance (P = .091), and the whole-body insulin sensitivity index (P = .091).
Dr. Koren and her colleagues also performed linear regression analyses, controlling for either waist circumference or weight. Sleep deprivation was still the most significant factor as measured on the 90-minute glucose tolerance test and by the whole-body insulin sensitivity index.
"The model suggests that these relationships between home sleep deprivation and insulin resistance or hyperglycemia are independent of obesity, generalized or central," said Dr. Koren.
She cited the example of a 15-year-old female subject, who was lean. Her sleep went from 8.7 hours at baseline to 7.9 hours with the restriction. Her glucose values did not change significantly between baseline and restriction, but her insulin levels were noticeably higher in the sleep-restricted state, said Dr. Koren. Those levels rose an hour into the 90-minute tolerance test, which suggests that she was insulin resistant and needed to secrete more insulin to maintain glycemia.
Dr. Koren and her colleagues hope to replicate the study in a larger cohort.
Dr. Koren reported no relevant financial conflicts.
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