Waking Day Research Articles

Intermittent Walking has Similar Effects on 24-Hour Glycemia as a Calorically Equivalent Continuous Walk in Older Adults

Older adults spend more time engaged in sedentary behavior (SB) than any other segment of the population. Interrupting sedentary time with short bouts of walking improves 24-hour glycemic control compared to uninterrupted sitting. However, it is not known if short-walking bouts are as beneficial to 24-hour glycemia as a single bout of continuous exercise. PURPOSE: To compare the effectiveness of multiple, short intermittent walking bouts and one, calorically equivalent continuous bout of walking on 24-hour glycemia in older adults. METHODS: Healthy, overweight/obese older adults (N=18, 67 ± 5 y, BMI = 32.2 ± 4,3 kg/m2) completed two, 24h conditions in a whole room indirect calorimeter; 1) Intermittent walking (IW): 1.5 min of moderate intensity treadmill walking (36 min total) every 30 minutes and 2) continuous walking (CW): 36 min continuous, moderate intensity treadmill walking performed in the morning (~8AM). Outside of the prescribed walking times, subjects remained in SB for the remainder of the waking day. Continuous glucose monitoring was used to measure interstitial glucose concentrations every 5 minutes. Energy and macronutrient intake was standardized between conditions. RESULTS: 24-hour energy expenditure (2257 ± 329 vs. 2165 ± 302 kcal, mean ± SD) and RQ (0.84 ± 0.03 vs. 0.84 ± 0.03) were similar during IW and CW, respectively. Peak postprandial glucose following dinner was lower (p<0.05) during IW (120.4 ± 10.7 mg/dl) compared to CW (135.3 ± 15.3 mg/dl). No differences were observed in any other 24 hour glycemia variables, including 24 hour area under the glucose curve (IW = 154862 ± 12724 mg/dl, CW = 158096 ± 15156 mg/dl), glycemic variability (standard deviation of 24 hour glucose concentrations) (IW = 12.2 ± 4.4 mg/dl, CW = 12.2 ± 4.2 mg/dl), and peak postprandial glucose concentrations following breakfast (IW = 144.0 ± 22.7 mg/dl, CW = 144.8 ± 27.2 mg/dl) and lunch (IW = 137.9 ± 17.1 mg/dl, CW = 139.2 ± 17.8 mg/dl). CONCLUSION: These results suggest IW had similar effects as CW on 24-hour glycemia, although the postprandial glucose response to meals consumed later in the day may be lower with IW. IW may improve cardiometabolic health in older adults.

0034 DISSOCIATING CIRCADIAN AND HOMEOSTATIC CONTRIBUTIONS TO PAIRED-ASSOCIATES LEARNING IN YOUNGER AND OLDER ADOLESCENTS USING 28-HOUR FORCED DESYNCHRONY

Learning is affected by sleep; less understood is the role of circadian timing. In adolescence, where learning is at a premium, marked shifts occur in both sleep and circadian biology. Understanding the roles these two systems play in learning across adolescence is important for both scientific and policy reasons. To this end, we used a forced desynchrony protocol in which independent and interacting effects of sleep and circadian rhythms can be separated. Learning was measured in 18 younger (11F; 9.6–13.4 [11.9 ± 1.0] years) and 18 older (8F; 13.5–15.9 [14.4 ± 0.67] years) adolescents who completed 12 cycles of forced desynchrony with 16.33 hours awake and 11.66 hours sleeping in each cycle to decouple sleep-wake timing from circadian rhythms. Every 2-hours during waking, participants learned 6 randomly presented word pairs and were asked to recall one word of each pair after a 10-minute delay. Memory was scored for successful recall (i.e., hits) and mismatched items (i.e., false alarms). Accuracy was calculated as the difference of hit and false alarm rates, indicating robustness of recall. Accuracy scores were z-scored within-participant and tagged for endogenous circadian phase (0°=dim light melatonin onset; 60° bins) and homeostatic load (hours awake; 3.5 hour bins). Accuracy scores were submitted to mixed-effects models assessing independent and interacting effects of circadian phase, homeostatic load, and age. Independent of circadian phase, memory accuracy deteriorated with time awake (F(4,2566.01) = 15.57, p<.001); no independent (F(5,2569.69) = 0.85, p = .51) nor interacting (F(20,2568.96) = 1.00, p=.47) circadian effects were observed. No main-effect of age was observed, yet a significant interaction of age and time awake (F(4,2566.01) = 2.49, p=.041) indicated older adolescents had an attenuated decay in the middle hours (~9 hours awake) of the waking day. These data demonstrate that effects of time awake on learning in adolescents are separable from circadian influences. Younger adolescents were more susceptible to the impact of homeostatic load than older adolescents. These data underscore the importance of considering developmental changes in sleep and circadian rhythms in policy and educational settings. These data were supported by R01MH52415, R01MH01358, R01MH076969, T32MH019927, K01MH109854.

0969 INDUCING MORE SLEEP ON SCHOOL NIGHTS REDUCES SEDENTARY BEHAVIOR WITHOUT AFFECTING MORE VIGOROUS PHYSICAL ACTIVITY IN SHORT- SLEEPING ADOLESCENTS

Nearly half of adolescents sleep less than 7 hours on school nights. Short sleep has been associated with obesity and we previously found that shortening sleep during summer months causes teens to eat more calories. However, there is concern that extending sleep may cut into physical activity time. Correlational findings are mixed on the relationship between sleep and physical activity during the school year, when short sleep is very common on school nights. Here we report results of a pilot study examining the impact of experimental sleep extension on the waking sedentary, light, and moderate/vigorous activity of habitually short-sleeping teens. Eighteen 14-17-year-olds who regularly slept 5–7 hours on school nights were enrolled in a 5-week protocol during the school year. Week 1 was a baseline to confirm habitual sleep. Participants then completed a pair of 2-week (weekday only) sleep conditions in a randomly counterbalanced order: Prescribed Habitual Sleep (HAB; school-night schedule matching baseline) and Sleep Extension (EXT; 1.5 hours longer in bed on school nights). Teens self-selected their weekend bedtimes. Teens wore wrist actigraphy to assess sleep fidelity and waist-mounted accelerometers to determine amounts of sedentary, light, moderate/vigorous activity during each condition. School night sleep averaged 6.16 hours during HAB and 7.34 hours during EXT (p<.001). Compared to HAB, during EXT teens averaged a 55 minute reduction in daily waking sedentary activity (p=.001) with a slight increase in light activity (7 minutes; p=.048) but no difference in moderate/vigorous activity (p=.53). Previous research indicates sedentary behavior is associated with obesity risk in teens. This pilot study indicates that, when short-sleeping teens sleep longer, they engage in less sedentary activity without seeming detriment in their moderate/vigorous activity. Further, other research suggests that risk for other negative consequences resulting from short sleep (i.e., higher caloric intake) may be attenuated. Cincinnati Children’s Research Foundation

New Zealanders working non-standard hours also have greater exposure to other workplace hazards

ABSTRACTExposure to workplace hazards, such as dust, solvents, and fumes, has the potential to adversely affect the health of people. However, the effects of workplace hazards on health may differ when exposure occurs at different times in the circadian cycle, and among people who work longer hours or who do not obtain adequate sleep. The aim of the present study was to document exposures to workplace hazards across a national sample of New Zealanders, comparing people who work a standard 08:00 −17:00 h Monday-to-Friday working week (Std hours) and those who do not (N-Std hours). New Zealanders (n = 10 000) aged 20–64 yrs were randomly selected from the Electoral Roll to take part in a nationwide survey of workplace exposures. Telephone interviews were conducted between 2004 and 2006, using a six-part questionnaire addressing demographics, detailed information on the current or most recent job (including exposures to a range of workplace hazards), sleep, sleepiness, and health status. N-Std hours were categorised on the basis of: being required to start work prior to 07:00 h or finish work after 21:00 h and/or; having a regular on-call commitment (at least once per week) and/or; working rotating shifts and/or; working night shift(s) in the last month. The response rate was 37% (n = 3003), with 22.2% of participants (n = 656) categorised as working N-Std hours. Industry sectors with the highest numbers of participants working N-Std hours were manufacturing, health and community services, and agriculture, fishing, and forestry. Response rate was 37% (n = 3003) with 22.2% (n = 656) categorised as working N-Std hours. Participants working N-Std hours were more likely to be exposed to all identified hazards, including multiple hazards (OR = 2.45, 95% CI = 2.01–3.0) compared to those working Std hours. Participants working N-Std hours were also more likely to report ‘never/rarely’ getting enough sleep (OR = 1.38, 95% CI = 1.15–1.65), ‘never/rarely’ waking refreshed (OR = 1.23, 95% CI = 1.04–1.47), and excessive sleepiness (OR = 1.77, 95% CI = 1.29–2.42). New Zealanders working N-Std hours are more likely to be exposed to hazards in the workplace, to be exposed to multiple hazards, and to report inadequate sleep and excessive sleepiness than their colleagues working a standard 08:00−17:00 h Monday-to-Friday working week. More research is needed on the effects of exposure to hazardous substances outside the usual waking day, on the effects of exposure to multiple hazards, and on the combination of hazard exposure and sleep restriction as a result of shift work.

The impact of sleep on novel concept learning

Prior research demonstrates that sleep benefits memory consolidation. But beyond its role in memory retention, sleep may also facilitate the reorganization and flexible use of new information. In the present study, we investigated the effect of sleep on conceptual knowledge. Participants classified abstract dot patterns into novel categories, and were later tested on both previously seen dot patterns as well as on new patterns. A Wake group (n=17) trained at 9AM, continued with their daily activities, and then tested at 9PM that evening. A Sleep group (n=20) trained at 9PM, went home to sleep, and was tested the following morning at 9AM. Two Immediate Test control groups completed testing immediately following training in either the morning (n=18) or evening (n=18). Post-training sleep led to superior classification of all stimulus types, including the specific exemplars learned during training, novel patterns that had not previously been seen, and “prototype” patterns from which the exemplars were derived. However, performance did not improve significantly above baseline after a night of sleep. Instead, sleep appeared to maintain performance, relative to a performance decline across a day of wakefulness. There was additionally evidence of a time of day effect on performance. Together with prior observations, these data support the notion that sleep may be involved in an important process whereby we extract commonalities from our experiences to construct useful mental models of the world around us.

Diurnal Variation and Twenty-Four Hour Sleep Deprivation Do Not Alter Supine Heart Rate Variability in Healthy Male Young Adults.

Heart rate variability (HRV) has become an increasingly popular index of cardiac autonomic control in the biobehavioral sciences due to its relationship with mental illness and cognitive traits. However, the intraindividual stability of HRV in response to sleep and diurnal disturbances, which are commonly reported in mental illness, and its relationship with executive function are not well understood. Here, in 40 healthy adult males we calculated high frequency HRV—an index of parasympathetic nervous system (PNS) activity—using pulse oximetry during brain imaging, and assessed attentional and executive function performance in a subsequent behavioral test session at three time points: morning, evening, and the following morning. Twenty participants were randomly selected for total sleep deprivation whereas the other 20 participants slept as normal. Sleep deprivation and morning-to-night variation did not influence high frequency HRV at either a group or individual level; however, sleep deprivation abolished the relationship between orienting attention performance and HRV. We conclude that a day of wake and a night of laboratory-induced sleep deprivation do not alter supine high frequency HRV in young healthy male adults.

Minimum Wear Duration for the activPAL Professional Activity Monitor in Adolescent Females.

This study aims to determine the minimum number of days of monitoring required to reliably predict sitting/lying time, standing time, light intensity physical activity (LIPA), moderate-to-vigorous intensity physical activity (MVPA) and steps in adolescent females. 195 adolescent females (mean age = 15.7 years; SD = 0.9) participated in the study. Participants wore the activPAL activity monitor for a seven day protocol. The amount of time spent sitting/lying, standing, in LIPA and in MVPA and the number of steps per day were quantified. Spearman-Brown Prophecy formulae were used to predict the number of days of data required to achieve an intraclass correlation coefficient of both 0.7 and 0.8. For the percentage of the waking day spent sitting/lying, standing, in LIPA and in MVPA, a minimum of 9 days of accelerometer recording is required to achieve a reliability of ≥ 0.7, while a minimum of 15 days is required to achieve a reliability of ≥ 0.8. For steps, a minimum of 12 days of recording is required to achieve a reliability of ≥ 0.7, with 21 days to achieve a reliability of ≥ 0.8. Future research in adolescent females should collect a minimum of 9 days of accelerometer data to reliably estimate sitting/lying time, standing time, LIPA and MVPA, while 12 days is required to reliably estimate steps.

Analysis of nocturnal actigraphic sleep measures in patients with COPD and their association with daytime physical activity

BackgroundSleep disturbances are common in patients with chronic obstructive pulmonary disease (COPD) with a considerable negative impact on their quality of life. However, factors associated with measures of sleep in...

Switching L-dopa Therapy from Pulsatile to Pulse Administration Reduces Motor Complications in Parkinson's Disease.

To evaluate the severity of wearing-off and dyskinesia in patients with complicated Parkinson disease (PD) after switching L-dopa oral therapy from a "pulsatile" administration, consisting in intermittent multiple daily small doses of the drug, to a "pulse" administration, consisting in standard oral doses given at specific interdose intervals. Thirty-four PD patients with motor complications were monitored twice with standardized waking day motor status evaluations using the Unified Parkinson Disease Rating Scale-Motor Examination (UPDRS-ME) and the Abnormal Involuntary Movement Scale (AIMS) after switching L-dopa administration modality from "pulsatile" to "pulse." To quantify predictable motor fluctuations, a Wearing Off Index was computed based on changes in treatment response magnitude. On the whole, after switching from "pulsatile" to "pulse" administration, there was a reduction in number of L-dopa daily doses and an increase in the amount of the dosage of the single doses, AIMS maximum score decreased without increasing motor disability. More specifically, in predominant fluctuating patients, there was a significant reduction in UPDRS-ME average score as well as in Wearing Off Index. In predominant dyskinetic patients, there was a significant reduction in average and maximum AIMS scores with no changes in average and maximum UPDRS-ME scores. Switching L-dopa therapy from "pulsatile" to "pulse" modality may reduce the severity of wearing-off and dyskinesia in complicated PD.

Sedation versus no sedation: Are there differences in relatives’ satisfaction with the Intensive Care Unit? A survey study based on data from a randomised controlled trial

Currently there is a trend towards less or no use of sedation of mechanically ventilated patients. Still, little is known about how different sedation strategies affect relatives' satisfaction with the Intensive Care Unit (ICU). To explore if there was a difference in relatives' personal reactions and the degree of satisfaction with information, communication, surroundings, care and treatment in the ICU between relatives of patients who receive no sedation compared with relatives of patients receiving sedation during mechanical ventilation in the ICU. A survey study using a questionnaire with 39 questions was distributed to relatives of mechanically ventilated patients, who had been randomised to either sedation with daily wake up or no sedation. Forty-nine questionnaires were sent out and 36 relatives answered. The response rate was 73%. We found no differences in relatives' personal reactions or in the degree of satisfaction with information, communication, care and treatment in the ICU between relatives of patients in the two groups. Relatives of patients treated with no sedation felt more bothered by disturbances in the surroundings compared with relatives of patients who were sedated (p=0.03). Treating the patient during mechanical ventilation with no sedation does not affect relatives' satisfaction adversely.

Efficacy and safety of levodopa-carbidopa intestinal gel from a study in Japanese, Taiwanese, and Korean advanced Parkinson's disease patients.

In a previous multinational, randomized, double-blind, double-dummy study, levodopa–carbidopa intestinal gel (LCIG) was tolerable and significantly improved ‘off’ time in advanced Parkinson’s disease (PD) patients. However, efficacy and safety in the Asian population has not yet been demonstrated. In this open-label study, efficacy and safety of LCIG were assessed in Japanese, Korean, and Taiwanese advanced PD patients with motor complications not adequately controlled by available PD medication. The patients were treated with LCIG monotherapy for 12 weeks. The primary end point was the mean change from baseline to week 12 in ‘off’ time, as reported in the PD Symptom Diary, normalized to a 16 h waking day and analyzed by a mixed-model repeated-measures analysis. Adverse events (AEs) were recorded. Thirty-one patients were enrolled (23 Japanese, 4 Taiwanese, 4 Korean) and 28 (90%) completed the study. For those who completed the study, the mean (s.d.) total daily levodopa dose from LCIG was 1,206.3 (493.6) mg/day at final visit (n=28); last observation carried forward (n=30) was 1,227.6 (482.8) mg/day. There was a significant mean change (s.d.) of −4.6 (3.0) hours of ‘off’ time from baseline (mean (s.d.)=7.4 (2.3)) to week 12 (n=29), P<0.001. All the patients had an AE, with the most frequently reported being incision site pain (42%); 1 (3.2%) discontinued treatment because of an AE and later died because of sepsis, which the investigator considered unrelated to LCIG treatment. These results suggest that LCIG is efficacious and tolerable in Japanese, Taiwanese, and Korean advanced PD patients.

SEDding Ourselves Up for Problems

SEDding Ourselves Up for Problems

SEDENTARY BEHAVIOUR – ARE WE SITTING TOO MUCH?

Sedentary behavior is defined as “Engaging in behaviors during the waking day that are done while sitting or reclining and result in little energy expenditure.” (Koster et al Diabetes Care,...

Circadian dynamics in measures of cortical excitation and inhibition balance

Several neuropsychiatric and neurological disorders have recently been characterized as dysfunctions arising from a ‘final common pathway’ of imbalanced excitation to inhibition within cortical networks. How the regulation of a cortical E/I ratio is affected by sleep and the circadian rhythm however, remains to be established. Here we addressed this issue through the analyses of TMS-evoked responses recorded over a 29 h sleep deprivation protocol conducted in young and healthy volunteers. Spectral analyses of TMS-evoked responses in frontal cortex revealed non-linear changes in gamma band evoked oscillations, compatible with an influence of circadian timing on inhibitory interneuron activity. In silico inferences of cell-to-cell excitatory and inhibitory connectivity and GABA/Glutamate receptor time constant based on neural mass modeling within the Dynamic causal modeling framework, further suggested excitation/inhibition balance was under a strong circadian influence. These results indicate that circadian changes in EEG spectral properties, in measure of excitatory/inhibitory connectivity and in GABA/glutamate receptor function could support the maintenance of cognitive performance during a normal waking day, but also during overnight wakefulness. More generally, these findings demonstrate a slow daily regulation of cortical excitation/inhibition balance, which depends on circadian-timing and prior sleep-wake history.

Identifying adults’ valid waking wear time by automated estimation in activPAL data collected with a 24 h wear protocol

The activPAL monitor, often worn 24 h d−1, provides accurate classification of sitting/reclining posture. Without validated automated methods, diaries—burdensome to participants and researchers—are commonly used to ensure measures of sedentary behaviour exclude sleep and monitor non-wear.We developed, for use with 24 h wear protocols in adults, an automated approach to classify activity bouts recorded in activPAL ‘Events’ files as ‘sleep’/non-wear (or not) and on a valid day (or not). The approach excludes long periods without posture change/movement, adjacent low-active periods, and days with minimal movement and wear based on a simple algorithm. The algorithm was developed in one population (STAND study; overweight/obese adults 18–40 years) then evaluated in AusDiab 2011/12 participants (n = 741, 44% men, aged >35 years, mean ± SD 58.5 ± 10.4 years) who wore the activPAL3™ (7 d, 24 h d−1 protocol). Algorithm agreement with a monitor-corrected diary method (usual practice) was tested in terms of the classification of each second as waking wear (Kappa; κ) and the average daily waking wear time, on valid days. The algorithm showed ‘almost perfect’ agreement (κ > 0.8) for 88% of participants, with a median kappa of 0.94. Agreement varied significantly (p < 0.05, two-tailed) by age (worsens with age) but not by gender. On average, estimated wear time was approximately 0.5 h d−1 higher than by the diary method, with 95% limits of agreement of approximately this amount ±2 h d−1.In free-living data from Australian adults, a simple algorithm developed in a different population showed ‘almost perfect’ agreement with the diary method for most individuals (88%). For several purposes (e.g. with wear standardisation), adopting a low burden, automated approach would be expected to have little impact on data quality. The accuracy for total waking wear time was less and algorithm thresholds may require adjustments for older populations.

A Retrospective Evaluation of the Frequency of Impulsive Compulsive Behaviors in Parkinson's Disease Patients Treated with Continuous Waking Day Apomorphine Pumps.

Impulsive compulsive behaviors (ICBs) can have a deleterious impact on the lives of patients with PD with orally active dopamine agonist treatment recognized as the greatest risk factor. However, the relationship between subcutaneous administration of the dopamine agonist, apomorphine, and impulsive compulsive behaviors is unknown. We conducted a retrospective analysis of 28 advanced PD patients treated with subcutaneous waking day apomorphine ambulatory minipumps at the National Hospital for Neurology and Neurosurgery (London, UK). Twelve of the patients had experienced impulsive compulsive behaviors before starting apomorphine. Reduction of oral dopamine agonist dose before apomorphine had led to complete resolution in 6 cases with no recurrence on long-term apomorphine maintenance therapy. Six patients still had active impulsive compulsive behaviors when apomorphine was started. Four of these improved, and in the other 2 there was no worsening. Of the 16 patients with no previous history of impulsive compulsive behaviors who started apomorphine, only 1, who was still receiving concurrent levodopa, developed impulsive compulsive behaviors. These data provide preliminary evidence that continuous apomorphine pump therapy has a lower proclivity to trigger or exacerbate impulsive compulsive behaviors than oral dopamine agonists. This is likely to be attributed to a more tonic stimulation of striatal dopamine receptors leading to desensitisation, but could also be attributed to a different pharmacological profile of apomorphine compared with orally active dopamine agonists. Apomorphine can be considered as a treatment option in patients who have developed disabling impulsive compulsive behaviors on oral agonist therapy whose motor handicap cannot be controlled adequately on l-dopa alone. Further prospective studies are needed to provide a definitive answer to this question.

Media device ownership and media use: Associations with sedentary time, physical activity and fitness in English youth.

The aim of this study was to determine whether ownership and use of electronic media were associated with sedentary time and cardiorespiratory fitness (fitness) in youth. We also aimed to determine if associations were independent of physical activity (PA).Fitness was measured using the 20 m shuttle-run. PA, sedentary time, ownership of media devices and media use were self-reported.Participants (n = 678, age 10–15 years) reported daily sedentary time of 620 (± 210) min. Forty-one percent of participants had low PA and 50.4% had low fitness.Higher weekend sedentary time was associated with low fitness in girls (p = 0.005) and boys (p < 0.001) and remained significant when adjusted for PA in the latter (p = 0.006). Using social media was associated with higher sedentary time in both sexes and low fitness in girls. High sedentary time was more likely (OR = 5.3, 95%CI: 2.0–14.4) in boys who owned game consoles. Low fitness was more likely in boys who owned digital/satellite TV receivers (OR = 1.8, 95%CI: 1.8–3.2).Schoolchildren spent > 10 h or ~ 85% of each waking day sedentary. Use of social media was associated with higher sedentary time in both sexes and with low fitness in girls. Reducing social media use in youth offers one potential target for intervention. Behaviours associated with sedentary time differed from predictors of low fitness. The complex and often sex-specific interactions identified between sedentary time, PA and fitness suggest the need for carefully targeted interventions to reduce sedentary time and improve fitness in English youth.

Objectively measured patterns of sedentary time and physical activity in young adults of the Raine study cohort

BackgroundTo provide a detailed description of young adults’ sedentary time and physical activity.Methods384 young women and 389 young men aged 22.1 ± 0.6 years, all participants in the 22 year old follow-up of the Raine Study pregnancy cohort, wore Actigraph GT3X+ monitors on the hip for 24 h/day over a one-week period for at least one ‘valid’ day (≥10 h of waking wear time). Each minute epoch was classified as sedentary, light, moderate or vigorous intensity using 100 count and Freedson cut-points. Mixed models assessed hourly and daily variation; t-tests assessed gender differences.ResultsThe average (mean ± SD) waking wear time was 15.0 ± 1.6 h/day, of which 61.4 ± 10.1 % was spent sedentary, 34.6 ± 9.1 % in light-, 3.7 ± 5.3 % in moderate- and, 0.3 ± 0.6 % in vigorous-intensity activity. Average time spent in moderate to vigorous activity (MVPA) was 36.2 ± 27.5 min/day. Relative to men, women had higher sedentary time, but also higher vigorous activity time. The ‘usual’ bout duration of sedentary time was 11.8 ± 4.5 min in women and 11.7 ± 5.2 min in men. By contrast, other activities were accumulated in shorter bout durations. There was large variation by hour of the day and by day of the week in both sedentary time and MVPA. Evenings and Sundays through Wednesdays tended to be particularly sedentary and/or inactive.ConclusionFor these young adults, much of the waking day was spent sedentary and many participants were physically inactive (low levels of MVPA). We provide novel evidence on the time for which activities were performed and on the time periods when young adults were more sedentary and/or less active. With high sedentary time and low MVPA, young adults may be at risk for the life-course sequelae of these behaviours.Electronic supplementary materialThe online version of this article (doi:10.1186/s12966-016-0363-0) contains supplementary material, which is available to authorized users.

Sedentary Behavior and Cardiovascular Risk in Older Adults: a Scoping Review.

Sedentary behavior is an emerging risk factor for cardiovascular disease (CVD) and may be particularly relevant to the cardiovascular health of older adults. This scoping review describes the existing literature examining the prevalence of sedentary time in older adults with CVD and the association of sedentary behavior with cardiovascular risk in older adults. We found that older adults with CVD spend >75 % of their waking day sedentary, and that sedentary time is higher among older adults with CVD than among older adults without CVD. High sedentary behavior is consistently associated with worse cardiac lipid profiles and increased cardiac risk scores in older adults; the associations of sedentary behavior with blood pressure, CVD incidence, and CVD-related mortality among older adults are less clear. Future research with larger sample sizes using validated methods to measure sedentary behavior are needed to clarify the association between sedentary behavior and cardiovascular outcomes in older adults.

Positive upshots of cortisol in everyday life.

Cortisol, the major physiological end product of the hypothalamic-pituitary-adrenal axis, is usually associated with stress and negative affect. However, a new body of research highlights the complex, adaptive significance of elevated cortisol within individuals in everyday life. Whereas most studies do not have the power to test the dynamic transactions between cortisol and affect within a person throughout the entire waking day, we employed an intensive study protocol analyzing hourly diary reports of affect in relation to hourly salivary cortisol samples among 24 healthy adults from morning to bedtime, across 2 consecutive weekdays (N = 862 total samples). Utilizing multileveling modeling and focusing on within-person effects, we examined whether momentary increases in cortisol could be mood protective, or energy enhancing, in everyday life, supporting the cortisol boost hypothesis. Results revealed no significant associations between cortisol and current affective state; however, within-person increases in cortisol were significantly associated with subsequent rises in activeness, alertness, and relaxation, and trend-level reductions in stress and nervousness. This study adds to growing evidence that cortisol plays a positive role in regulating affect in everyday life. (PsycINFO Database Record