Effects of a carbohydrate-enriched night meal on sleepiness and sleep duration in night workers: A double-blind intervention

Abstract

The aim of this study was to investigate the effects of an intervention involving night meal composition on sleepiness and sleep duration in night security guards. A total of 54 male night security guards with a mean age of 30.8 years (SD = 5.5 years) filled out a 24-h dietary recall and were submitted to anthropometric measurement. Twenty-four workers were assigned to the intervention. The intervention was carried out over three consecutive weeks under three conditions. On the first week, no change in workers' food composition was introduced. On the second week, the amount of carbohydrates was increased by 20-30% compared with the first week's intake, whereas during the third week protein intake was increased by 30-40% compared with baseline levels (first week). Throughout the study period, workers wore an actigraph device to estimate sleeping and waking times. A two-factor mixed model analysis with sleep duration as the outcome showed an interaction effect between body mass index (BMI) and condition (F2,56 = 3.9; p = 0.03). Sleep duration was higher in obese workers compared with nonobese workers during the Carbohydrate condition (357 and 267 min, respectively). The analysis of variance (ANOVA) showed an increase in sleepiness under all conditions at 3:00 h (F1,276 = 165.73; p < 0.01) postprandially. A significant difference in sleepiness was also found between the obese and nonobese groups (F1,276 = 14.8; p < 0.01). The effect of the night meal content on sleep duration seems to be mediated by BMI. A carbohydrate-rich meal increased the duration of sleep in obese workers, and may therefore also influence sleepiness.

Dietary Macronutrients and Sleep

“…In that study, higher protein intakes resulted in fewer wake episodes (Lindseth et al, 2013). Similarly, in Nehme et al’s (2014) study of night security guards over 3 weeks using Actigraphs, high protein meals induced significantly fewer wake episodes compared with a (baseline) control diet; and the carbohydrate-rich meals induced significantly longer sleep durations. Another Actigraph study using 24-hr food recalls to measure macronutrient intakes of 240 adolescents, resulted in carbohydrate kilocalories leading to shorter sleep durations when average daily increases of fat followed with a concomitant decrease in carbohydrate kilocalories (Weiss et al, 2010).…”

“…Our results are in agreement with prior reports showing carbohydrate diet consumption resulted in shorter wake times and high fat diets resulted in longer wake times. However, there is conflicting data (Landström et al, 2000; Lindseth et al, 2013; Nehme et al, 2014; Rontoyanni, Baic, & Cooper, 2007; Voderholzer et al, 1998; Weiss et al, 2010). …”

“…Some studies have indicated that high carbohydrate diets had a positive impact on sleep latencies (Lindseth, Lindseth, & Thompson, 2013; Nehme et al, 2014), whereas other studies showed no significant relationship or a negative relationship between carbohydrate consumption and sleep onset (Afaghi, O’Connor, & Chow, 2007; Phillips et al, 1975). In Lindseth and colleagues’ (2013) study, Actigraphs were used to measure the sleep and activity levels of 40 healthy young adults.…”

“…The researchers found that high carbohydrate intakes led to shorter sleep latencies than a control diet and higher protein intakes resulted in fewer wake episodes. Nehme and colleagues (2014) studied 24 night security guards ( M age = 30.8 years) for 3 weeks using Actigraph devices and found that complex carbohydrate diets resulted in significantly longer sleep durations that improved the sleep quality of obese workers when compared with other diets (Nehme et al, 2014). …”

“…Some investigators believe that dietary modifications might lead to better quality sleep (Grandner, Jackson, Gerstner, & Knutson, 2014; Shi, McEvoy, Luu, & Attia, 2008). Although some studies have suggested that the macronutrient (the body’s fuel and major building blocks: carbohydrates, fats, and proteins [Molnar, 2006]) content of food intakes may affect both the quality and quantity of sleep (Crispim et al, 2011; Markus et al, 2005; Nehme et al, 2014), other studies have produced mixed results (Adam & Oswald, 1979; Landström, Knutsson, & Lennernäs, 2000; Santana et al, 2012). Therefore, this study focused on the effects of specific macronutrients on sleep.…”