None listed
Conditions
Brief summary
Our modern 24h society means that sleep and waking activities are changing. Ten million Australian workers sit at work, eleven million Australians are sleep restricted and 1.9 million Australians are shiftworkers. This is problematic, as prolonged sitting and sleep restriction have negative impacts on health and safety at work and contribute to a huge burden on public health. Although sleep restriction and prolonged sitting have been investigated separately, to date, no study has investigated how these factors jointly impact health and safety. To investigate the combined effects of prolonged sitting and sleep restriction in different shiftwork types, this study measures cardiometabolic outcomes and cognitive performance in healthy adults doing dayshifts or nightshifts under different levels of sleep restriction and in conditions of prolonged sitting and conditions of breaking up sitting. We propose that breaking up sitting will improve cardiometabolic health and cognitive performance compared to prolonged sitting, but this effect will be lessened under conditions of sleep restriction. These results inform the development of workplace policy and public health guidelines targeting prolonged sitting at work and the impacts on health and safety.
Interventions
This is a 7 day in-laboratory between-subjects design where participants will be randomly allocated at the study run condition to a shift-type condition (simulated dayshift or simulated nightshift) and a sleep opportunity condition (5h time in bed, or 9h time in bed). At the individual level, participants will also be allocated to a physical activity level (sedentary or breaking up sitting). All combinations of these conditions will be explored, with a total of 8 conditions (2 x 2 x 2).
Partic
This is a 7 day in-laboratory between-subjects design where participants will be randomly allocated at the study run condition to a shift-type condition (simulated dayshift or simulated nightshift) and a sleep opportunity condition (5h time in bed, or 9h time in bed). At the individual level, participants will also be allocated to a physical activity level (sedentary or breaking up sitting). All combinations of these conditions will be explored, with a total of 8 conditions (2 x 2 x 2). Participants will live in the laboratory for 7 days, with all participants experiencing an adaption day on the first day and a recovery day on day 7. On the adaption day participants will sleep for 9h from 10pm to 7am and participants will have a recovery sleep on day 6 from 10pm to 7am. During the experimental protocol (days 2-6) participants in the dayshift condition will work 8h dayshifts from 9am to 5pm and sleep each night on days 2-6 from 9h (10pm to 7am) or 5h (2am-7am) depending on sleep opportunity condition. Participants in the nightshift condition will work an 8h shift during the night on days 2-6 from 10pm to 6am and sleep during the day on days 2-6 for 9h (8am to 5pm) or 5h (12pm to 5pm) depending on sleep opportunity condition. All participants in the nightshift condition will also have a 2h nap opportunity on day 1 from 3pm to 5pm and a 2h nap opportunity on day 6 from 9am to 11am. During the 8h dayshifts and nightshifts (days 2-6) all participants will complete a 20-min cognitive performance test battery involving tests of reaction time and working memory, and subjective rating scales of alertness. Participants will perform a simulated driving task at 8am and 5:30pm in the dayshift condition, and at 9pm and 6:30am in the nightshift condition. Every 30min during each 8h dayshift and nightshift participants in the breaking up sitting condition will perform 3mins of light-intensity physical activity on a motorised treadmill (walking at 3.2km/h). In the sedentary condition participants will stay seated during the 8h shift, with the exception of walking to the kitchen or bathroom. During shift-times when participants are not breaking up sitting or completing cognitive test batteries they have free time where they can watch movies, read books, play board games and talk to other participants. Participants were supervised at all times by at least one research staff member, and research staff will instruct participants on the timing of performance tests and breaking up sitting. A combination of actigraphy and polysomnography was used to monitor sleep during all sleep periods.
Sponsors
Central Queensland University
Study design
Allocation
Randomised controlled trial
Intervention model
Parallel
Primary purpose
Prevention
Masking
Open (masking not used)
Eligibility
Sex/Gender
All
Age
18 Years to 35 Years
Healthy volunteers
Yes
Inclusion criteria
Adults aged 18-35 years, BMI normal to overweight (20-30kg/m2), non-smoker, no current health concerns including no previous or current diagnosis of psychiatric and/or neurological problems or sleep disorder, habitual bedtime between 10pm to 12am and habitual waketime between 6am and 8am, no shiftwork in the previous three months, no current medication use, consumption of less than 10 standard alcoholic beverages/week, caffeine consumption less than 3 cups/day, no habitual napping habits, no trans-meridian travel in the previous 4 weeks, fluent English speaker, not pregnant, no contraindications to exercise, low levels of daily physical activity, greater than 6 hours of sitting time per day
Exclusion criteria
Subjects who report one or more of the following: current smoker, serious health concerns, previous or current diagnosis of psychiatric and/or neurological problems, or sleep disorders, less than 18 years old or over 35 years old, BMI less than 18 or greater than 30kg/m2, habitual bedtime outside of 10pm-12am or habitual wake times outside of 6am to 8am, current shiftwork or shiftwork in the last three months, currently taking any glucose and/or lipid lowering medication, or any medication/drugs that may influence sleep or are known to impact the central nervous system, consumption of greater than 10 standard alcoholic beverages/week, caffeinated beverage consumption greater than 3 cups/day, history of habitual napping, trans-meridian travel in the past 4 weeks, not fluent in English, pregnant.
Outcome results
None listed