Overnight weight loss: relationship with sleep structure and heart rate variability

Walter Moraes,Dalva Poyares,Christian Guilleminault,Adriana Rueda,Agostinho Rosa,Marco Tulio Mello,Sergio Tufik

doi:10.1038/npre.2008.2342.1

Walter Moraes, Dalva Poyares + Show 5 more

Open Access

https://doi.org/10.1038/npre.2008.2342.1

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Abstract

Abstract Background: Weight loss can be caused by a loss of body mass due to metabolism and by water loss as unsensible water loss, sweating, or excretion in feces and urine. Although weight loss during sleep is a well-known phenomenon, it has not yet been studied in relation to sleep structure or autonomic tonus during sleep. Our study is proposed to be a first step in assessing the relationship between overnight weight loss, sleep structure, and HRV (heart rate variability) parameters. Methods: Twenty-five healthy volunteers received a 487 kcal meal and 200 ml water before experiment. Volunteers were weighed before and after polysomnography. Absolute and relative weight indices were calculated. Time and frequency domain analysis of heart rate variability was assessed during stages 2, 4, and REM. Nonparametric linear regression analysis was performed between night weight loss parameters, polysomnographic, and HRV ariables. Results: HF correlated positively with weight loss during stage 4. Slow wave sleep duration correlated positively with weight loss and weight loss rate. The duration of Stage 2 correlated negatively with absolute and relative weight loss. Conclusions: Weight loss during sleep is dependent upon sleep stage duration and sleep autonomic tonus. Slow-wave sleep and sleep parasympathetic tonus may be important for weight homeostasis.

Highlights

Weight loss can be caused by a loss of body mass due to metabolism and by water loss as unsensible water loss, sweating, or excretion in feces and urine
This is the first study to report that overnight weight loss is dependent upon sleep structure
We found that weight loss during sleep was a universal phenomenon, its magnitude was affected by sleep stages and autonomic tonus

Summary

Introduction

Weight loss can be caused by a loss of body mass due to metabolism and by water loss as unsensible water loss, sweating, or excretion in feces and urine. Studies on the variation of body composition over 24 hours using bioimpedance methods showed an increase in weight and a reduction in height during daytime.[3,4] In these studies, bioimpedance was influenced by food and drink ingestion.[3,4,5] Many studies assessed the effects of sleep debt on metabolism and weight gain for long periods of time, suggesting that it may cause obesity and metabolic syndrome but there are no studies for the effects during short periods.[6,7,8] There is evidence suggesting a homeostatic mechanism for weight control in animal models and humans.[9,10] This mechanism is thought to be dependent on energy intake, energy expenditure, and environmental conditions In this context, sleep homeostasis could influence this process.[9,10] Autonomic tonus varies according to different sleep stages and influences overnight fluid loss, blood pressure, and heart rate variability.[12,13,14] HRV (heart rate variability) is an easy-to-access non-invasive marker of the autonomic tonus during sleep.[12,13,14] Our study is proposed as a first step in assessing the relationship between overnight weight loss, sleep structure, and HRV parameters

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Results

Conclusion