“Our data support an optimization of sleep duration and timing in order to prevent metabolic disorders like obesity and type 2 diabetes” – Wilms and colleagues, 2018

Did you know that nearly a third of Americans report getting less than six hours of sleep per night? And there’s growing evidence that losing sleep doesn’t just make you feel and look fatigued. (Thinking twice about those late night holiday parties?) Sleep loss can also affect your metabolic health.

Poor or disrupted sleep is a risk factor for obesity and other chronic diseases such as diabetes. A sort of “jet lag” or disrupted morning-to-evening gene expression in our fat tissue may be partly to blame. In a brand new study published by german researchers in The Journal of Clinical Endocrinology & Metabolism, 15 healthy men under the age of 30 who underwent sleep restriction (4 hours of sleep) or sleep deprivation (no sleep) for a night experienced gene expression changes in their fat tissue. In particular, sleep restriction and especially sleep deprivation disrupted circadian rhythms, or normal morning-to-evening cycles, in the metabolism of carbohydrates in these men’s white adipose tissue. This was despite the fact that the men did not gain weight or change their dietary habits during the study.

“Up to 19% of genes associated with energy turnover in WAT [white adipose tissue] were morning-to-evening and sleep regulated. […] Our data suggest enhanced glucose breakdown and lipogenesis [the metabolic formation of fat] in the morning after a night with short or no sleep, respectively.” – Wilms and colleagues, 2018

In the sleep deprivation condition, study participants were allowed to read and watch movies while sitting, but were not allowed to eat or engage in brisk physical activity. The researchers found that with sleep deprivation for a single night, study participants exhibited an upregulation in genes associated with carbohydrate breakdown. Glucose breakdown is usually high after you eat or exercise, whereas long-lasting fat metabolism is a healthy characteristic of sleep time. The sleep deprived men also had an upregulation in genes associated with fat formation or lipogenesis, a propensity toward inflammation with increased levels of an adipokine called retinol-binding-protein 4 (RBP4), and insulin resistance with a diminished capacity to secrete insulin from their liver beta cells. These are all common characteristics or precursors of diabetes.

Of interest, weight loss and consumption of antioxidants like green tea and yogurts with Vitamin D have been associated with lower RBP4 levels.

“In line with the present study, it has been previously shown that two nights of sleep restriction with only four hours of sleep induce an insulin resistant state in the human adipocyte together with a reduction of total body insulin sensitivity.” – Wilms and colleagues, 2018

Fat cells and insulin. Credit: Ugreen.

Overall this study demonstrated that even a single night of no sleep can dampen or disrupt our normal morning-to-evening metabolism cycles. Extended periods of sleep restriction may do the same. In other words, without adequate sleep our body becomes confused in its expression of genes that tell our cells what types of fuel sources to use when.

Did you know that eating out of time with the light-dark cycle and the “master clock” in your brain (which is set by exposure to light) can also cause metabolic dysfunction? This is partly because when you eat at times you should be resting/sleeping (like late at night), the local “clocks” or circadian rhythms in the activity of your gut, liver, fat and muscle get out of sync with the master clock in your brain. This causes traffic jams and metabolic confusion. Should I be burning sugars right now? Or burning fats as I sleep? Am I sleeping? Am I awake? So confused…

“Desynchronization of the suprachiasmatic nucleus master clock in the brain and peripheral circadian clocks in liver, fat, and skeletal muscle cells may increase the risk of chronic diseases. Feeding signals appear to be the dominant timing cue for the rhythms of peripheral clocks, including those that control metabolic pathways.” — Patterson & Sears, 2017

“Time-restricted feeding has been shown to restore transcriptome rhythms in the liver of sleep-restricted rodents. There is evidence that time restricted feeding induces differential changes in gene expression.” – Wilms and colleagues, 2018

Learn more about metabolic health, circadian rhythms and how dietary interventions like time-restricted feeding may help here. Learn more about sleep hygiene practices from LIFE app user and longevity guru Zora Benhamou here.