The Skinny on Sleep and Body Fat

This guest post is by Dan Pardi of Dan’s Plan, a smart approach to food, movement and sleep to achieve and sustain your ideal weight.

Sleep Impacts Body Weight and Metabolism

Getting a Good Night's Sleep Might Help, Too

There is good evidence that less sleep is associated with higher body mass index (BMI). Even short-term sleep restriction has been shown to produce physiological changes that can increase body weight. Some of these changes include:

• Reduced ability to metabolize blood sugar (impaired glucose tolerance, like in diabetes)
• Increased blood pressure
• Activation of the sympathetic nervous system (the “fight or flight” system)
• Increased activation of inflammatory processes (that can also promote increases in body weight)
• Changes in weight-related hormones, such as decreased leptin and increased ghrelin (both the decreases in leptin and the increases in ghrelin can stimulate increased appetite, respectively)

Thus, it is likely that even relatively mild and infrequent sleep restriction over time can alter physiological processes such as sugar metabolism and hormone release, which in turn affect appetite and weight gain.

Types of Sleep Deprivation

Before we explore this connection further, let’s review the three main ways in which sleep is typically restricted.

1. Sleep fragmentation – this occurs when the normal progression and sequences of sleep stages is disrupted, such as from some sleep disorders.
2. Loss of specific stages of sleep – for example, certain psychiatric medications selectively reduce Rapid Eye Movement (REM) sleep.
3. Voluntary sleep curtailment – the result of getting less sleep due to work, travel, social activities, or from simply watching too much TV at night.

Sleep Loss Even Affects Fat Cells

To explore the mechanisms of sleep restriction on sugar metabolism and hormone sensitivity fat cells, Broussard et al., from the University of Chicago studied seven young, healthy, normal-weight volunteers. Calorie intake and physical activity were controlled while sleep was experimentally manipulated under three conditions:

1. Baseline sleep, no restriction: 4 nights of 8.5 hours of sleep
2. Selective deep sleep restriction: 4 nights of 8.5 hours of sleep, but without deep sleep. A disruptive noise was played when a subject entered deep sleep – this would not awaken the subject but instead inhibit deep sleep from taking place. However, subjects got the same amount of total sleep as the baseline condition (8.5 hours). This procedure is essentially testing the specific importance of deep sleep on the outcome measure (fat cell sensitivity to insulin).
3. Total sleep restriction: 4 nights of 4.5 hours of sleep.

At the end of each sleep condition, fat from underneath the skin was extracted with a large needle (ouch!) and analyzed. In all 7 subjects, when the fat samples from the baseline condition were compared to the fat samples from either sleep-disrupted conditions, both sleep-disrupted fat cell samples showed signs of decreased sensitivity to insulin – cells became more diabetic-like.

This is the first demonstration of how sleep disruption can affect the sensitivity of fat cells to insulin, which in turn can impact body weight by influencing how your body stores the nutrients you consume. Given the recent, drastic increases in average body weights as a growing global concern, it is important to identify important contributors to this phenomenon and sleep deprivation is undoubtedly on the list.

Dan Pardi, PhD Candidate in the Neurology Department at Leiden University Medical Center in The Netherlands and the CEO of Dan’s Plan: A smart approach to food, movement and sleep to help you achieve and sustain your ideal weight.

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NOTE from Dan: In the middle of September, I travel to Portugal to attend the European Sleep Research Society meeting. I plan to report back on further cutting edge findings on the sleep-weight relationship after I return. Stay tuned!

Citation:

Broussard J, Day A, Brady M, Van Cauter E, Tasali E. Experimental reduction of sleep duration or quality is associated with impaired insulin signaling in the adipocyte. Sleep 2009, Suppl. 32; A130.

Tagged as: Dan's Plan, Fat, Weight