Influence of Carbohydrate on the Stages of Sleep – A Meta-Analysis
Abstract
Carbohydrate is the nutrient most commonly said to influence sleep: it is proposed that a high intake increases the uptake of tryptophan by the brain, where it is metabolized into serotonin and melatonin. As this mechanism depends on the relative amount of carbohydrate and protein, studies were reviewed where diets differed in these macro-nutrients.
The Web of Science and Medline were interrogated using terms related to carbohydrate and sleep. Papers were retained if two diets, differing in the percentage of calories coming from carbohydrate, had been contrasted using either polysomnography or actigraphy. Measures considered with polysomnography included sleep onset time; sleep efficiency; rapid eye-movement (REM) and slow wave sleep (SWS). Measures examined from actigraphy included: sleep efficiency; duration of sleep. Meta-analysis was conducted using Review Manager 5.2 (Cochrane) using a random-effects model.
With the polysomnography measures six studies met the inclusion criteria. A lesser consumption of carbohydrate was associated with more SWS (SMD = 0.47; CI 0.06 – 0.88; P = 0.02; I2 = 0%) and less REM (SMD = – 0.47, CI –0.87– –0.07, P = 0.02, I2 = 0%). A lower intake of carbohydrate was also associated with a shorter time before falling asleep (P = 0.03; I2 0%). Sleep efficiency is the percentage of time spent asleep, relative to the total time in bed. Using polysomnography there was a trend for better sleep efficiency to be associated with with a lower intake of…
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Evidence Hub reads this as a meta-analysis. Its evidence level is 1 of 5 (Highest · pooled evidence). Pooled evidence from several studies sits at the top of the evidence pyramid.
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