Light Exposure and Metabolic dysfunction @ יואל קסלר
Light Exposure and Metabolic dysfunction @ יואל קסלר

Background

It has long been known that sleeping with the lights or television on may negatively effect sleep quality, however the physiologic consequences are not entirely clear. In a new publication reprinted here at Light Exposure and Metabolic dysfunction @ יואל קסלר , Mason et.al published in the Proceedings of the National Academy of Sciences data that explains the extent of the physiologic damage of that poor sleep.

What was studied?

Mason examined a group of young adults who were exposed to low level light for two consecutive nights while they slept. They then examined measures of sleep quality, serum glucose, and measures of insulin resistance.

What was found?

The authors demonstrated that even a single night of low light exposure during sleep led to an increase in insulin resistance and impaired glucose homeostasis. This suggests that prolonged exposure to light during sleep could be a cause of significant cardiometabolic disease over time.

The full abstract can be seen below or at the PNAS site here.

"Ambient nighttime light exposure is implicated as a risk factor for adverse health outcomes, including cardiometabolic disease. However, the effects of nighttime light exposure during sleep on cardiometabolic outcomes and the related mechanisms are unclear. This laboratory study shows that, in healthy adults, one night of moderate (100 lx) light exposure during sleep increases nighttime heart rate, decreases heart rate variability (higher sympathovagal balance), and increases next-morning insulin resistance when compared to sleep in a dimly lit (<3 lx) environment. Moreover, a positive relationship between higher sympathovagal balance and insulin levels suggests that sympathetic activation may play a role in the observed light-induced changes in insulin sensitivity.

Abstract

This study tested the hypothesis that acute exposure to light during nighttime sleep adversely affects next-morning glucose homeostasis and whether this effect occurs via reduced sleep quality, melatonin suppression, or sympathetic nervous system (SNS) activation during sleep. A total of 20 young adults participated in this parallel-group study design. The room light condition (n = 10) included one night of sleep in dim light (<3 lx) followed by one night of sleep with overhead room lighting (100 lx). The dim light condition (n = 10) included two consecutive nights of sleep in dim light. Measures of insulin resistance (morning homeostatic model assessment of insulin resistance, 30-min insulin area under the curve [AUC] from a 2-h oral glucose tolerance test) were higher in the room light versus dim light condition. Melatonin levels were similar in both conditions. In the room light condition, participants spent proportionately more time in stage N2 and less in slow wave and rapid eye movement sleep. Heart rate was higher and heart rate variability lower (higher sympathovagal balance) during sleep in the room light versus the dim light condition. Importantly, the higher sympathovagal balance during sleep was associated with higher 30-min insulin AUC, consistent with increased insulin resistance the following morning. These results demonstrate that a single night of exposure to room light during sleep can impair glucose homeostasis, potentially via increased SNS activation. Attention to avoiding exposure to light at night during sleep may be beneficial for cardiometabolic health."

More interesting articles can be found on our Blog.

As well as: "Data on Benefits of Exercise in the Elderly"

זה זמן רב ידוע ששינה עם האורות או הטלוויזיה דולקת עשויה להשפיע לרעה על איכות השינה, אולם ההשלכות הפיזיולוגיות אינן ברורות לחלוטין. בפרסום חדש מוצגים נתונים המסבירים את היקף הנזק הפיזיולוגי של אותה שינה לקויה. המחברים הוכיחו שאפילו לילה בודד של חשיפה נמוכה לאור במהלך השינה הוביל לעלייה בתנגודת לאינסולין ולפגיעה בהומאוסטזיס של גלוקוז. זה מצביע על כך שחשיפה ממושכת לאור במהלך השינה יכולה להיות גורם למחלה קרדיומטבולית משמעותית לאורך זמן.

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