None listed
Conditions
Brief summary
Humans require sufficient sleep to maintain physical and mental health. Reductions in sleep quantity and quality are associated with reduced cognitive function and productivity and increased absenteeism, along with chronic diseases such as hypertension and cardiovascular disease, dementia, depression and anxiety. Laboratory studies have shown that hot temperatures result in worse sleep, with epidemiological data suggesting that hot overnight conditions are independently related to mortality. To date, nearly all solutions for combatting heat stress are pre-occupied with reducing air temperature – usually using air conditioning (AC). Currently, despite no supporting evidence, all major international public health agencies (including WHO) state that fans should be turned OFF above 32-35°C as they accelerate heat/dehydration risk. A series of recent publications from our research group has shown that fans can mitigate heat stress at temperatures as high as 42°C. However, how these findings translate to overnight fan use at these temperatures remains unknown. Thus, the purpose of this trial is to test the use of electric fans to improve sleep quantity and quality in ambient conditions of 35°C and 40% Relative Humidity.
Interventions
The trial will be conducted in a climate chamber located in the Susan Wakil Health Building at the University of Sydney. Participants will undergo four (4) overnight sleeps in the climate chamber. This will consist of two habituation sleeps and two experimental conditions.
Night 1: Habituation sleep in thermoneutral conditions (18-24°C)
Night 2: Experimental sleep in hot conditions (35°C, 40% RH)
1 month washout period
Night 3: Habituation sleep in thermoneutral conditions (18-24°C)
Night 4: Exp
The trial will be conducted in a climate chamber located in the Susan Wakil Health Building at the University of Sydney. Participants will undergo four (4) overnight sleeps in the climate chamber. This will consist of two habituation sleeps and two experimental conditions. Night 1: Habituation sleep in thermoneutral conditions (18-24°C) Night 2: Experimental sleep in hot conditions (35°C, 40% RH) 1 month washout period Night 3: Habituation sleep in thermoneutral conditions (18-24°C) Night 4: Experimental sleep in hot conditions (35°C, 40% RH) Night 1 and 2 will occur on consecutive nights. Participants will return 1 month later and complete nights 3 and 4 on consecutive nights. The habituation sleeps will occur in thermoneutral conditions with full instrumentation, to allow participants to be accustomed to sleeping in the chamber. The habituation sleeps will not include the use of the fan. The experimental conditions will always occur following a habituation night. During one of the experimental conditions, participants will have access to a pedastal fan pointed towards them (intervention). In the other experimental condition, the same fan will be pointed away (control). This will occur in a random order for each participant. In the intervention condition, the fan will be placed 2m away from the participant. The fan will be used continuously for 11 hours, between 8:30pm and 7:30am. Participants will be able to self-select their preferred air velocity with a remote control. Participants will be able to change their set velocity throughout the night. Participants will not be able to view the speed setting. The minimum air velocity that can be selected is 0.4 m/s, through to a maximum of 4 m/s. Air velocity will be continuously monitored by three anemometers positioned at the side of the bed, between the pedestal fan and the participant. This will be used to determine the preferred speed of each participant.
Sponsors
The University of Sydney
Study design
Allocation
Randomised controlled trial
Intervention model
Crossover
Primary purpose
Prevention
Masking
Blinded (masking used) (Subject, Investigator, Outcomes Assessor)
Eligibility
Sex/Gender
All
Age
18 Years to 40 Years
Healthy volunteers
Yes
Inclusion criteria
1. Between the ages of 18-40 years 2. Able to understand the demands of the protocol, has had any questions answered and has voluntarily signed the participant consent form prior to any study procedures 3. Must have a usual sleep time before midnight, a self-reported sleep latency of 30min or less, and a usual waketime between 5am and 8am
Exclusion criteria
1. Insomnia Severity Index score greater than or equal to 8, due to possible clinical insomnia 2. Pittsburgh Sleep Quality Index score <5 3. Noise Sensitivity as identified by Weinstein Noise Sensitivity Scale (WNSS), with a score greater than or equal to 5 in question 5 or 19 4. Reported sleep or circadian disorders 5. Taking any medication(s) known to affect sleep or thermoregulation 6. Mood disorders known to affect sleep, such as depression, anxiety and stress. Identified by greater than normal levels of Depression (greater than or equal to 5), Anxiety (greater than or equal to 3) and Stress (greater than or equal to 7) as indicated by DASS-21 7. Known cardiovascular or respiratory disease 8. Acute illness on study visit days 9. Neurodiversity (e.g., ADHD, autism) 10. Substance-abuse disorders 11. Type I or Type II Diabetes 12. Faecal incontinence or rectal prolapse 13. A contraindication to the telemetric temperature pill a. Weigh less than 40kg b. Intestinal disorders that can lead to the obstruction of the digestive tract, including diverticula c. Motility disorder(s) of the gastrointestinal tract d. Have undergone surgical procedures in the gastrointestinal tract or having such medical history (esophagus, stomach, intestines) e. Known swallowing disorders f. Chron’s disease g. Pacemaker or electro-medical implant h. May undergo strong electromagnetic field during the period of use of the system (MRI in particular) i. Pregnant women
Outcome results
None listed