Social Jetlag, Chronotype, and Cardiometabolic Risk

In the paper

“Evening chronotype was associated with younger age, lower family income, later average bed time and later average wake time, greater sleep debt, poorer sleep quality, greater depressive symptomology, and less physical activity (P Ͻ .05).”

In the paper

“68 participants (15.2%) had an earlier midsleep on free days relative to workdays”

In the paper

“neither chronotype nor SJL was related significantly to resting heart rate or BP (P Ͼ .05).”

In the paper

“In accord with previous reports, we found greater SJL linked to earlier wake times and shorter sleep durations on workdays, as well as later wake times and longer sleep duration on free days (P Ͻ .05)(14).”

What the sources say

• Not checked yetcites [14] Roenneberg, 2003, Life between clocks: daily temporal patterns of human chronotypes, J Biol Rhythms source

In the paper

“greater alcohol consumption, with higher glucose and lower HDLcholesterol”

In the paper

“In accord with previous reports, we found greater SJL linked to earlier wake times and shorter sleep durations on workdays, as well as later wake times and longer sleep duration on free days (P Ͻ .05)(14).”

What the sources say

• Not checked yetcites [14] Roenneberg, 2003, Life between clocks: daily temporal patterns of human chronotypes, J Biol Rhythms source

In the paper

“healthy adults asked to eat and sleep 12 hours out of phase from their regular schedules exhibited vascular and endocrine abnormalities, such as increased arterial pressure, a reversed daily cortisol rhythm, and postprandial glucose levels in the range of a prediabetic state (8).”

What the sources say

• Not checked yetcites [8] Scheer, 2009, Adverse metabolic and cardiovascular consequences of circadian misalignment, Proc Natl Acad Sci USA source

In the paper

“Chronotype quantified by the CSM has been validated with respect to variation in the diurnal rhythms of body temperature and subjective alertness (26).”

What the sources say

• Not checked yetcites [26] Natale, 2001, Additional validity evidence for the composite scale of morningness, Pers Individ Dif source

In the paper

“A global PSQI score Ͼ 5 indicates poor sleep quality.This threshold has a diagnostic sensitivity of 89.6% and specificity of 86.5%, distinguishing between healthy controls (good sleepers) and patients reporting sleep complaints (poor sleepers) (27).”

What the sources say

• Not checked yetcites [27] Buysse, 1989, The Pittsburgh Sleep Quality Index: a new instrument for psychiatric practice and research, Psychiatry Res source

In the paper

“Evening types are also more likely to be depressed (10), overweight (11), diabetic, and hypertensive (12), in comparison to morning types.”

What the sources say

• Not checked yetcites [10] Levandovski, 2011, Depression scores associate with chronotype and social jetlag in a rural population, Chronobiol Int source
• Not checked yetcites [11] Roenneberg, 2012, Social jetlag and obesity, Curr Biol source
• Not checked yetcites [12] Merikanto, 2013, Associations of chronotype and sleep with cardiovascular diseases and type 2 diabetes, Chronobiol Int source

In the paper

“The CSM has both high internal consistency (Cronbach ␣ Ͼ 0.80) and test-retest reliability (r Ͼ 0.88) (25).”

What the sources say

• Not checked yetcites [25] Di Milia, 2013, Reviewing the psychometric properties of contemporary circadian typology measures, Chronobiol Int source

In the paper

“This instrument has high reliability (33) and convergent validity with several objective measures of physical activity and fitness, including maximal oxygen uptake (34) and body mass index (BMI) (35).”

What the sources say

• Not checked yetcites [33] Ainsworth, 1993, Accuracy of the College Alumnus Physical Activity Questionnaire, J Clin Epidemiol source
• Not checked yetcites [34] Nowak, 2010, Paffenbarger Physical Activity Questionnaire as an additional tool in clinical assessment of patients with coronary artery disease treated with angioplasty, Kardiol Pol
• Not checked yetcites [35] Choo, 2010, Longitudinal relationship between physical activity and cardiometabolic factors in overweight and obese adults, Eur J Appl Physiol source

In the paper

“SJL has been linked to measures of adiposity (11,15,16), heart rate (16,17), and higher cortisol levels in healthy individuals (16) and to higher glycated hemoglobin levels in patients with type 2 diabetes (18).”

What the sources say

• Not checked yetcites [11] Roenneberg, 2012, Social jetlag and obesity, Curr Biol source
• Not checked yetcites [15] Parsons, 2015, Social jetlag, obesity and metabolic disorder: investigation in a cohort study, Int J Obes (Lond) source
• Not checked yetcites [16] Rutters, 2014, Is social jetlag associated with an adverse endocrine, behavioral, and cardiovascular risk profile?, J Biol Rhythms source
• Not checked yetcites [17] Kantermann, 2013, Atherosclerotic risk and social jetlag in rotating shift-workers: First evidence from a pilot study, Work source
• Not checked yetcites [18] Reutrakul, 2013, Chronotype is independently associated with glycemic control in type 2 diabetes, Diabetes Care source

In the paper

“The Paffenbarger questionnaire is predictive of health conditions that are related to physical activity, including myocardial infarction (36), and total cholesterol and fasting blood glucose (35).”

What the sources say

• Not checked yetcites [36] Chomistek, 2011, Vigorous physical activity, mediating biomarkers, and risk of myocardial infarction, Med Sci Sports Exerc source
• Not checked yetcites [35] Choo, 2010, Longitudinal relationship between physical activity and cardiometabolic factors in overweight and obese adults, Eur J Appl Physiol source

In the paper

“This instrument estimates customary intake of diverse nutrients and food groups, with item content developed from the NHANES 1999 -2002 dietary recall data (37,38).”

What the sources say

• Not checked yetcites [37] Block, 1990, A reduced dietary questionnaire: development and validation, Epidemiology source
• Not checked yetcites [38] Block, 1990, Validation of a self-administered diet history questionnaire using multiple diet records, J Clin Epidemiol source

In the paper

“The PSQI has high internal consistency (Cronbach ␣ ϭ 0.83) and test-retest reliability (r ϭ 0.85) (27).”

What the sources say

• Not checked yetcites [27] Buysse, 1989, The Pittsburgh Sleep Quality Index: a new instrument for psychiatric practice and research, Psychiatry Res source

In the paper

“The CESD has high internal consistency (Cronbach ␣ ‫؍‬ 0.87) (40).”

What the sources say

• Not checked yetcites [40] Radloff, 1977, The CES-D Scale: A Self-Report Depression Scale for Research in the General Population, Appl Psychol Meas source

In the paper

“Taken together, a disruption in the circadian system triggered by SJL could dysregulate the temporal organization of both central and peripheral rhythms and, in turn, promote metabolic abnormalities.”

In the paper

“At the molecular level, the central clock (in the suprachiasmatic nucleus) and peripheral oscillators throughout the body comprise a self-sustaining network of transcriptional-translational feedback loops that drive 24-hour expression patterns of core clock genes (47).”

What the sources say

• Not checked yetcites [47] Lowrey, 2004, Mammalian circadian biology: elucidating genome-wide levels of temporal organization, Annu Rev Genomics Hum Genet source

In the paper

“Thus, our findings suggest that SJL heightens metabolic risk through a misalignment in circadian rhythms rather than by sleep disturbances per se.”

In the paper

“the HOMA-IR index is a steadystate measure of baseline insulin and glucose function”

What the sources say

• Not checked yetcites [42] Wallace, 2004, Use and abuse of HOMA modeling, Diabetes Care source

In the paper

“Objective measures of circadian phase were unavailable in this sample, and it is unclear whether the individuals with SJL and/or self-reported evening chronotypes differ in their biological circadian phase.”

In the paper

“Given that hemodynamic and metabolic factors show circadian rhythms and that individuals vary in the timing of these rhythms, it is possible that our method of collecting samples within the same morning time frame across all participants (ie, irrespective of chronotype) may have led to an underestimation of variability in cardiometabolic risk factors and thus the effects of chronotype.”

In the paper

“Lastly, the cross-sectional design of the current study precludes causal inferences and warrants future prospective studies to extend the present findings.”

In the paper

“postprandial, dynamic measures such as the oral glucose tolerance test quantify the dynamic interplay of insulin sensitivity and ␤-cell insulin secretion (42).”

What the sources say

• Not checked yetcites [42] Wallace, 2004, Use and abuse of HOMA modeling, Diabetes Care source

In the paper

“Our results, along with other recent reports, suggest that a misalignment of the biological and socially influenced sleep timing is an additional factor contributing to risk for developing obesity, type 2 diabetes, and atherosclerotic cardiovascular disease and highlight the potential for sleep and circadian-focused interventions in preventative health care.”

In the paper

“The use of actigraphy to quantify SJL is a strength of the current study.”

In the paper

“In addition, the current study quantified average caloric intake and energy expenditure but did not examine the timing of these activities.”

In the paper

“The timing of meals serves as a behavioral zeitgeber that can entrain peripheral clocks (51).”

What the sources say

• Not checked yetcites [51] Buhr, 2013, Molecular components of the mammalian circadian clock source

In the paper

“Emerging evidence from both rodent and human studies suggests that food consumption during habitual sleep or rest times (ie, evenings in humans) is associated with greater risk for obesity (49,50)”

What the sources say

• Not checked yetcites [49] Arble, 2009, Circadian timing of food intake contributes to weight gain, Obesity source
• Not checked yetcites [50] Baron, 2011, Role of sleep timing in caloric intake and BMI, Obesity source

In the paper

“There is evidence that both fasting and postprandial glucose measures are predictive of type 2 diabetes, and these may represent two distinct risk factors that may contribute to diabetes via different physiological mechanisms (43).”

What the sources say

• Not checked yetcites [43] Meyer, 2006, Different mechanisms for impaired fasting glucose and impaired postprandial glucose tolerance in humans, Diabetes Care source

In the paper

“Regions throughout the brain have autonomous circadian oscillators that re-entrain at different rates when they are isolated and then re-exposed to light cues (48).”

What the sources say

• Not checked yetcites [48] Abe, 2002, Circadian rhythms in isolated brain regions, J Neurosci source

In the paper

“Previous reports have also linked other sleep disorders, such as sleep apnea, with poor health outcomes (46).”

What the sources say

• Not checked yetcites [46] Troxel, 2010, Sleep symptoms predict the development of the metabolic syndrome, Sleep source