Circadian adaptation to night shift work is associated with higher REM sleep duration.

OBJECTIVE: To investigate the influence of the degree of circadian adaptation to night work on sleep architecture following night shift. METHODS: Thirty four night workers (11 females; 33.8 ± 10.1years) completed a simulated night shift following 2-7 typical night shifts. Participants completed a laboratory-based simulated night shift (21:00-07:00 hours), followed by a recovery sleep opportunity (∼09:00-17:00 hours), recorded using polysomnography. Urinary 6-sulphatoxymelatonin (aMT6s) rhythm acrophase was used as a marker of circadian phase. Sleep duration and architecture were compared between individuals with aMT6s acrophase before (unadapted group, n = 22) or after (partially adapted group, n = 12) bedtime. RESULTS: Bedtime occurred on average 2.16 hours before aMT6s acrophase in the partially adapted group and 3.91 hours after acrophase in the unadapted group. The partially adapted group had more sleep during the week before the simulated night than the unadapted group (6.47 ± 1.02 vs. 5.26 ± 1.48 hours, p = .02). After the simulated night shift, both groups had similar total sleep time (partially adapted: 6.68 ± 0.80 hours, unadapted: 6.63 ± 0.88 hours, p > .05). The partially adapted group had longer total rapid eye movement sleep duration than the unadapted group (106.79 ± 32.05 minutes vs. 77.90 ± 28.86 minutes, p = .01). After 5-hours, rapid eye movement sleep accumulation was higher in the partially adapted compared to the unadapted group (p = .02). Sleep latency and other stages were not affected by circadian adaptation. DISCUSSION: Partial circadian adaptation to night shift was associated with longer rapid eye movement sleep duration during daytime sleep, highlighting the influence of entrainment between the sleep-wake cycle and the circadian pacemaker in night workers. The findings have important implications for sleep and subsequent alertness associated with shift work.

Night shift work and immune response to the meningococcal conjugate vaccine in healthy workers: a proof of concept study.

BACKGROUND: It is well-established that sleep regulates immune functions. Immunological functions are dependent on circadian rhythms and regular sleep as both have an impact on the magnitude of immune responses following antigenic challenge (eg, in vaccination). Here we investigated whether nocturnal shift work can influence post-vaccination response. METHODS: Thirty-four healthy workers (23 females) working either nocturnal or diurnal shifts (17 in each group) received the meningococcal C meningitis vaccine. Sleep was recorded polysomnographically (PSG) and with actigraphy. Humoral and cellular responses were assessed after vaccination. RESULTS: Night workers showed decreased N3 stage and REM sleep duration, increased inflammatory mediators (TNF-α and IL-6 levels), and a weak specific humoral response to vaccination associated with reduced CD4 T lymphocytes, reduced plasmacytoid dendritic cells, reduced prolactin levels, increased TReg and increased IL-10 levels. In addition, the decrease in total sleep time and circadian rhythm alterations were associated with a reduced humoral response post-vaccination. CONCLUSIONS: Our findings provide novel evidence concerning immune alterations of shift work on workers' health based on real-life circumstances. In association with circadian components, sufficient sleep time and rhythm synchronization were important for the development of the Ag-specific immune response, suggesting that the humoral response to vaccination may be impaired in individuals with chronic sleep restriction and circadian misalignment.

Association between inflammatory potential of the diet and sleep parameters in sleep apnea patients.

OBJECTIVES: The aim of this study was to analyze the association between the inflammatory potential of diet and sleep parameters in individuals with obstructive sleep apnea (OSA) and to evaluate the sensitivity and specificity of the dietary inflammatory index (DII) at predicting sleep pattern. METHODS: Patients diagnosed with mild to severe OSA were included in the study (N = 296). Sleep pattern was analyzed by polysomnography and subjective sleep parameters. DII scores were calculated from a validated food frequency questionnaire. Receiver operating characteristic curve analysis and generalized linear models were conducted. RESULTS: DII scores were efficient at predicting apnea severity (P < 0.05) and daytime sleepiness (P = 0.02) in age stratification and predicting rapid eye movement latency in obese individuals (P = 0.03). No significant associations were found between DII scores and the majority of sleep parameters. The DII was only associated with daytime sleepiness; patients with a more proinflammatory diet (quintile 4) showed more subjective sleepiness than the group with a more anti-inflammatory diet (quintile 1; P < 0.05). CONCLUSION: Findings from this study indicated that the DII could be sensitive and specific for predicting apnea severity in individuals commonly associated with OSA. Although the DII was not associated with most of the sleep parameters, the few associations found demonstrated the need for more studies that evaluate whether DII is associated with the risk for OSA symptoms.

Effect of the intake of high or low glycemic index high carbohydrate-meals on athletes' sleep quality in pre-game nights.

This study investigated the effect of the intake of high (HGI) or low glycemic index (LGI) high-carbohydrate meals on athletes' sleep. Nine basketball adult male athletes were assessed during a championship and received high-carbohydrate meals (dinner and evening snack) with HGI or LGI. Quantitative and qualitative sleep variables were assessed: sleep latency (LAT), sleep efficiency (EFIC), Wake After Sleep Onset (WASO), sleep time through actigraphy and sleep diary. Dietary intake, satiety, sleepiness, glycemic response, salivary cortisol and melatonin were also assessed. On both days most athletes had LAT and WASO higher than recommendation, and nocturnal sleep time below the recommendations. There was no difference between sleep and hormonal parameters according to GI dietary manipulations; however, correlations were observed between sleep and diet. Daily energy intake had negative correlation with efficiency and nocturnal total sleep time, and a positive correlation with WASO, regardless of the GI nocturnal meals. No differences were observed in salivary cortisol and melatonin according to GI. The results suggest that food intake throughout the day seems to exert more influence on sleep parameters of basketball players than GI manipulation of evening meals on the pre-night game, but further studies are necessary to better understand this complex relationship.

Dietary disinhibition mediates the relationship between poor sleep quality and body weight.

BACKGROUND: Inadequate sleep independently influences eating habits and weight status. However, the relationship between these three factors has not been well quantified. The objective of this study was to examine if eating behavior (i.e. dietary restraint, disinhibition and hunger) mediates the relationship between sleep and body mass index (BMI) in a large sample of American adults. METHOD: Cross-sectional data from the Nathan Kline Institute Rockland sample were assessed (n = 602; 38.9 ±â€¯14.5 years). Self-reported sleep and eating behavior were measured using the Pittsburgh Sleep Quality Index and Three Factor Eating Questionnaire, respectively. Path analysis was used to examine relationships amongst the construct, with mediation tested via bootstrapped confidence intervals. RESULTS: Poorer sleep quality was associated with both greater hunger (P = 0.03) and higher disinhibited eating (overeating in the presence of palatable foods or other disinhibiting stimuli like emotional stress; P < 0.001) behaviors. Higher disinhibited eating behavior was also associated with higher BMI (P < 0.001). There was a significant indirect relationship between sleep quality and BMI via disinhibition (b [95% CI] = 0.13 [0.06, 0.21], P = 0.001). No significant effects were found when total sleep time or time in bed were replaced as predictors in the mediation model. CONCLUSION: Disinhibited eating behavior mediated the relationship between sleep quality and weight status in both males and females. This mediation was due to aspects of sleep quality other than duration. These results suggest that improving sleep quality may benefit weight loss by helping to reduce an individuals' susceptibility to overeating.

Standardization of the Food Composition Database Used in the Latin American Nutrition and Health Study (ELANS).

Between-country comparisons of estimated dietary intake are particularly prone to error when different food composition tables are used. The objective of this study was to describe our procedures and rationale for the selection and adaptation of available food composition to a single database to enable cross-country nutritional intake comparisons. Latin American Study of Nutrition and Health (ELANS) is a multicenter cross-sectional study of representative samples from eight Latin American countries. A standard study protocol was designed to investigate dietary intake of 9000 participants enrolled. Two 24-h recalls using the Multiple Pass Method were applied among the individuals of all countries. Data from 24-h dietary recalls were entered into the Nutrition Data System for Research (NDS-R) program after a harmonization process between countries to include local foods and appropriately adapt the NDS-R database. A food matching standardized procedure involving nutritional equivalency of local food reported by the study participants with foods available in the NDS-R database was strictly conducted by each country. Standardization of food and nutrient assessments has the potential to minimize systematic and random errors in nutrient intake estimations in the ELANS project. This study is expected to result in a unique dataset for Latin America, enabling cross-country comparisons of energy, macro- and micro-nutrient intake within this region.