None listed
Conditions
Brief summary
The overarching aim of this project is to investigate a strategy to help maximise human cognitive performance in an encapsulated shift-work environment through evidence-based LED lighting design interventions optimised to support successful circadian physiology entrainment. We will conduct a randomised counter-balanced crossover experimental study designed to investigate the effectiveness of standard versus optimised LED lighting systems on cognitive performance, circadian entrainment, and objective sleep parameters during an 8 day simulated shift-work schedule in a laboratory environment.
Interventions
The intervention is lighting throughout a simulated submarine night shift (optimised lighting versus control lighting) on four night shifts during an eight-day laboratory protocol administered by sleep technicians. The optimised lighting intervention will be high intensity lighting (>200 lux) in the ‘cool’ blue-end wavelength range of the light spectrum during the times that we want to shift circadian rhythms (i.e. during the four x 8-hour work shifts) via automated adjustment to the laboratory
The intervention is lighting throughout a simulated submarine night shift (optimised lighting versus control lighting) on four night shifts during an eight-day laboratory protocol administered by sleep technicians. The optimised lighting intervention will be high intensity lighting (>200 lux) in the ‘cool’ blue-end wavelength range of the light spectrum during the times that we want to shift circadian rhythms (i.e. during the four x 8-hour work shifts) via automated adjustment to the laboratory lighting. During other times, the intervention lighting will be dimmed (<100lux) and the spectral content will be less ‘cool’ to avoid circadian shifts in the opposite direction than is intended. During the night shifts, participants will complete cognitive performance tasks, such as reaction time tasks and solving simple arithmetic equations. Adherence will be assessed via continuous video recording of the laboratory. All participants will experience the intervention condition, with a four-week wash-out period between the intervention and the control condition (counter-balanced).
Sponsors
Flinders University
Study design
Allocation
Randomised controlled trial
Intervention model
Crossover
Primary purpose
Treatment
Masking
Open (masking not used)
Eligibility
Sex/Gender
All
Age
18 Years to 70 Years
Healthy volunteers
Yes
Inclusion criteria
• Age, 18 years and older • Defence Navy eligibility requirements o Upper age-limit compatible with minimum service requirements o Australian Citizen o Passed year 10 English and Maths o Normal health and fitness o BMI >18.5 and <32.9 kg/m² • Report normal sleep (typical habitual sleep time of 6-8 hours, with a typical bedtime between 10pm-12am. • Willing and agree to follow protocol requirements, including; o Screening assessments o Home testing o Strict time and activity schedules (sleep, activity/work, mealtime) during each 8-day in-laboratory visit.
Exclusion criteria
• Language difficulties that may preclude informed consent. • Any severe cognitive impairments, mental illnesses, or intellectual disabilities that may preclude informed consent. • Self-reported sleep disorder (prior diagnosis of insomnia, obstructive sleep apnea, restless legs syndrome or any other recognised clinical sleep problem). • Extreme evening/morning types (according to screening questionnaire measures). • Shift work in the past 6 months, or intentions to undertake shift work prior to study completion. • International travel (>2 hour time shift) in the last 6 months, or anticipated travel prior to study completion. • Any relevant history of psychiatric, neurological, heart, or lung diseases/disorders. • Any significant eye- or cervical spine related disease, disorder or surgery that may interfere with simulated Defence work-shift schedules or circadian physiology. • Habitual caffeine consumption >250 mg (~2-3 cups of coffee) per day. • Current or recent (last 6 months) smoker. • Unwilling or unable to abstain from alcohol or any other recreational drug during the laboratory components of the study. • Reported use of any drugs or medications that may impact sleep (e.g. benzodiazepines, ‘z-drugs’, melatonin, anti-psychotics, anti-depressants).
Outcome results
None listed