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Background/Objective: Reduced sleep is a strong and independent risk factor for weight gain and obesity. Maternal obesity preconception and throughout gestation can increase the risk of adverse pregnancy outcomes and impact on offspring health in later life. This study investigated the relationship between sleeping behaviour and macronutrient intake in childbearing aged women. Subjects/Methods: We used cross-sectional data from the Australian Longitudinal Study on Women's Health 1973-78 cohort, aged 31-36 years in 2009 (n=8200). Subjective sleeping behaviour was reported and macronutrient intake was measured using a validated food frequency questionnaire. Latent class analysis (LCA) was used to derive sleeping patterns. Multivariate regression analysis was used to investigate the relationships between sleep and macronutrient intake. Results: LCA identified three sleep patterns: (LC1) average sleep (~8 h) with no adverse sleep-related symptoms (n=3570); (LC2) average sleep (~8 h) with sleeping difficulties and severe tiredness (n=2109); and (LC3) short sleep (~6 h) with sleeping difficulties and severe tiredness (n=915). In fully adjusted models, LC2 was inversely associated with percentage energy as protein (b=-0.24; P=0.01) and the protein-to-carbohydrate ratio (b=-0.01; P Conclusions: Sleeping behaviour patterns were associated with macronutrient intake in childbearing aged women. Improved sleep patterns, together with diet and physical activity strategies, may make it easier for women to achieve a balanced diet and optimise their weight status in preparation for pregnancy., Author(s): C J Bennett [sup.1] , H Truby [sup.1] , Z Zia [sup.2] , S W Cain [sup.3] , M L Blumfield [sup.1] Author Affiliations: (1) Department of Nutrition and [...]

We describe the time course of bone formation marker (P1NP) decline in men exposed to ~ 3 weeks of sleep restriction with concurrent circadian disruption. P1NP declined within 10 days and remained lower with ongoing exposure. These data suggest even brief exposure to sleep and circadian disruptions may disrupt bone metabolism., Introduction: A serum bone formation marker (procollagen type 1 N-terminal, P1NP) was lower after ~ 3 weeks of sleep restriction combined with circadian disruption. We now describe the time course of decline., Methods: The ~ 3-week protocol included two segments: "baseline," ≥ 10-h sleep opportunity/day × 5 days; "forced desynchrony" (FD), recurring 28 h day (circadian disruption) with sleep restriction (~ 5.6-h sleep per 24 h). Fasted plasma P1NP was measured throughout the protocol in nine men (20-59 years old). We tested the hypothesis that PINP would steadily decline across the FD intervention because the magnitude of sleep loss and circadian misalignment accrued as the protocol progressed. A piecewise linear regression model was used to estimate the slope (β) as ΔP1NP per 24 h with a change point mid-protocol to estimate the initial vs. prolonged effects of FD exposure., Results: Plasma P1NP levels declined significantly within the first 10 days of FD ([Formula: see text] = - 1.33 μg/L per 24 h, p < 0.0001) and remained lower than baseline with prolonged exposure out to 3 weeks ([Formula: see text] = - 0.18 μg/L per 24 h, p = 0.67). As previously reported, levels of a bone resorption marker (C-telopeptide (CTX)) were unchanged., Conclusion: Sleep restriction with concurrent circadian disruption induced a relatively rapid decline in P1NP (despite no change in CTX) and levels remained lower with ongoing exposure. These data suggest (1) even brief sleep restriction and circadian disruption can adversely affect bone metabolism, and (2) there is no P1NP recovery with ongoing exposure that, taken together, could lead to lower bone density over time.

Background: Misalignment of circadian timing in patients with depression has commonly been reported, but the underlying mechanisms are not known. Individual differences in the sensitivity of the circadian system to light affect how the biological clock synchronizes with the external environment and can lead to misalignment of rhythms. We investigated the sensitivity of the circadian system to light in unmedicated (for >3 months) women with a current or previous diagnosis of major depression, and healthy controls., Methods: Baseline melatonin levels in dim light (<1 lux) were assessed, followed by melatonin levels in normal indoor lighting of 100 lux in order to determine melatonin suppression., Results: Patients currently experiencing a depressive episode showed significantly lower levels of melatonin suppression to light compared to remitted patients and controls, with large effect sizes. Remitted patients and controls showed similar suppression., Limitations: The relatively small sample, and lack of long-term, within subject assessments, make it difficult to determine the potential causal role of reduced light sensitivity in the development of circadian disruption., Conclusions: We conclude that hyposensitivity of the circadian system to light may contribute to circadian misalignment in patients with depression. Interventions that increase sensitivity to light or provide stronger light cues may assist in normalizing circadian clock function., (Copyright © 2019. Published by Elsevier B.V.)

Associations among personality, diurnal preference, and circadian phase were investigated using a constant routine laboratory protocol. One hundred and sixty-eight healthy participants aged 18-30 years (Women n = 68) completed either a 30- or 50-hour constant routine under dim-light conditions (<3 lux), during which circadian phase was measured from core body temperature and melatonin. Prior to laboratory admission, self-report measures of personality and diurnal preference were also obtained. The personality trait of Constraint correlated positively with morning diurnal preference and earlier circadian phase, with circadian phase partially mediating the relationship between Constraint and diurnal preference. No other personality variables correlated with circadian phase. Sex was an important covariate in several of the relationships investigated due to lower levels of Constraint and later CBT phase amongst men and was thus controlled for in all relevant analyses. Findings from this highly controlled study are consistent with previous field research in suggesting that earlier circadian phase is associated with the personality trait of Constraint.