RecruitingACTRN12624000538549

Effect of an electric fan on sleep quality in hot overnight environments in young healthy adults


Sponsor

The University of Sydney

Enrollment

30 participants

Start Date

May 20, 2024

Study Type

Interventional

Conditions

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.


Eligibility

Sex: Both males and femalesMin Age: 18 YearssMax Age: 40 Yearss

Plain Language Summary

Simplified for easier understanding

Hot nights make it hard to sleep, and poor sleep in the heat is more than just uncomfortable — it is linked to serious health consequences including heart disease, cognitive decline, and even increased risk of death during heat waves. Most public health advice recommends turning fans off above 32 to 35 degrees Celsius, warning they increase dehydration risk. But recent research from the University of Sydney has challenged this, showing fans can actually help the body cope with extreme heat. This study will test, in a controlled laboratory setting, whether using an electric fan improves sleep quality and quantity on hot nights simulating 35 degrees Celsius at 40% relative humidity. Participants will spend nights in the research sleep lab and have their sleep measured objectively alongside body temperature and other physiological markers. You may be eligible if you are a healthy adult aged 18 to 40 who falls asleep before midnight, wakes between 5 and 8am, and doesn't have major sleep problems. People with insomnia, sleep disorders, cardiovascular or respiratory conditions, diabetes, mood disorders affecting sleep, or those taking medications that affect sleep or body temperature regulation are not eligible.

This summary was AI-generated to explain the trial in plain language. It is not medical advice. Always discuss eligibility with your doctor before enrolling in a clinical trial.

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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. Thi

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.


Locations(1)

NSW, Australia

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ACTRN12624000538549


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