The Supreme Importance of Sleep

Sleeping it off

At UC Berkeley’s Sleep and Neuroimaging Laboratory, a team looked into how sleep deprivation impairs the brain, specifically in regard to food choices. Twenty-three adults took part, undergoing functional magnetic resonance imaging after a good night’s sleep and after a night of inadequate sleep. They were shown how to indicate their relative desire for various food items and were watched by the fMRI to see if any brain disturbances took place. Here’s what was learned:

Results show that sleep deprivation significantly impaired brain activity in the frontal lobe, a region critical for controlling behavior and making complex choices, such as the selection of food to eat. The study suggests that sleep loss may prevent the higher brain functions normally critical for making appropriate food choices, rather than necessarily changing activity in deeper brain structures that react to basic desire.

Writing for Smithsonian magazine, Claudia Kalb described a University of Munich study that examined the sleeping habits of 65,000 adults, a hefty number. What they found was plenty of “social jet lag,” which Prof. Till Roenneberg of the Institute of Medical Psychology describes as “the chronic clash between what our bodies need (more sleep) and what our lives demand (being on time).”

Our daily lives are ruled by two physical phenomena: the earth’s rotation and the circadian clocks inside us. The internal clocks are finely tuned, and when we violate them, things never get better. There is a great deal more to be said on that subject, but we are interested in the correlation with obesity. It was already known that body weight and sleep deprivation share some kind of link. The University of Munich research team went beyond that and found a couple of new wrinkles. Kalb writes that of the 65,000 subjects, a sizable majority experienced a circadian disruption:

Two-thirds of them suffered from social jet lag, experiencing at least a one-hour disparity between how long they slept on workdays and weekends.

Roenneberg’s team concludes that it isn’t just how much sleep people get that matters — it’s how much they mess with their internal clocks. For every hour of social jet lag accrued, the risk of being overweight or obese rises by about 33 percent…. Obesity results from a host of influences, but Roenneberg says “one contributing factor is not living according to your biological temporal needs.”

For kids, the importance of sleep is even bigger, and not just any old sleep, says an Australian study previously discussed by Childhood Obesity News. It has to be “right time” sleep, that much is clear, though there may be different ways to interpret the data. Citing lead researcher Carol Maher, Scientific American writes:

[I]t was not the amount of sleep that mattered, it was timing. Children who went to bed early and got up early were far healthier than those who went to bed late and got up late, even though the two groups got the same amount of sleep.

It could be that those who go to sleep later spend more time watching television. Mornings tend to be better for exercise, whereas evenings are prime computer and television times — which means less exercise, more snacking, and more exposure to food marketing. But … it could also mean that kids who are more physically active during the day tend to get tired earlier, and go to bed earlier.

Getting back to grownups, a reader once quoted his nutritionist:

If you’re not hydrated and not sleeping enough, I don’t even want to talk to you.

Your responses and feedback are welcome!

Source: “MRI scans show how sleep loss affects the ability to choose proper foods,”, 06/10/12
Source: “Your Alarm Clock May Be Hazardous to Your Health,”, January 2013
Source: “Hidden Drivers of Childhood Obesity Operate Behind the Scenes,”, 10/31/11
Image by Vernon Swanepoel


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OVERWEIGHT: What Kids Say explores the obesity problem from the often-overlooked perspective of children struggling with being overweight.

About Dr. Robert A. Pretlow

Dr. Robert A. Pretlow is a pediatrician and childhood obesity specialist. He has been researching and spreading awareness on the childhood obesity epidemic in the US for more than a decade.
You can contact Dr. Pretlow at:


Dr. Pretlow’s invited presentation at the American Society of Animal Science 2020 Conference
What’s Causing Obesity in Companion Animals and What Can We Do About It

Dr. Pretlow’s invited presentation at the World Obesity Federation 2019 Conference:
Food/Eating Addiction and the Displacement Mechanism

Dr. Pretlow’s Multi-Center Clinical Trial Kick-off Speech 2018:
Obesity: Tackling the Root Cause

Dr. Pretlow’s 2017 Workshop on
Treatment of Obesity Using the Addiction Model

Dr. Pretlow’s invited presentation for
TEC and UNC 2016

Dr. Pretlow’s invited presentation at the 2015 Obesity Summit in London, UK.

Dr. Pretlow’s invited keynote at the 2014 European Childhood Obesity Group Congress in Salzburg, Austria.

Dr. Pretlow’s presentation at the 2013 European Congress on Obesity in Liverpool, UK.

Dr. Pretlow’s presentation at the 2011 International Conference on Childhood Obesity in Lisbon, Portugal.

Dr. Pretlow’s presentation at the 2010 Uniting Against Childhood Obesity Conference in Houston, TX.

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