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Trial registered on ANZCTR


Registration number
ACTRN12624000538549
Ethics application status
Approved
Date submitted
5/04/2024
Date registered
30/04/2024
Date last updated
23/06/2024
Date data sharing statement initially provided
30/04/2024
Type of registration
Prospectively registered

Titles & IDs
Public title
Effect of an electric fan on sleep quality in hot overnight environments in young healthy adults
Scientific title
Effect of an electric fan on sleep quality in hot overnight environments in young healthy adults
Secondary ID [1] 310987 0
Nil known
Universal Trial Number (UTN)
Trial acronym
OEF
Linked study record

Health condition
Health condition(s) or problem(s) studied:
thermoregulation 332089 0
sleep disturbance 332090 0
dehydration 333420 0
thermal comfort 333421 0
cognitive function 333443 0
Condition category
Condition code
Public Health 328814 328814 0 0
Other public health
Neurological 330239 330239 0 0
Studies of the normal brain and nervous system

Intervention/exposure
Study type
Interventional
Description of intervention(s) / exposure
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.
Intervention code [1] 327431 0
Treatment: Devices
Comparator / control treatment
During the control experimental condition (35°C, 40% RH), a fan will be placed 2m away from the participant, but will point away from the participant. This is to be in line with recommendations from various public health organisations to avoid pointing fans directly at you when the air temperature is 35°C or above.

All other aspects of the experimental condition will be the same, including the recording of air velocity, and monitoring of the participant.

The fan will be used continuously for 11 hours, between 8:30pm and 7:30am. Participants will not be able to change the speed of the fan. The fan speed will be set to provide an air velocity of 0.8 m/s measured at 2m away from the fan, however this air velocity will not impact the participant.
Control group
Active

Outcomes
Primary outcome [1] 336615 0
Total sleep time
Timepoint [1] 336615 0
Total sleep time will be measured in all trials, including habituation and experimental trials.

The Nox A1 will be set to start recording at 8:30pm, and will record data continuously for 11 hours until 7:30am.

During the experimental trials, this will record data for the entire period of fan use.
The same time period will be captured during habituation trials, where participants are sleeping in thermoneutral conditions without a fan.
Secondary outcome [1] 428978 0
Thermal Comfort
Timepoint [1] 428978 0
Thermal comfort will be collected during both habituation and experimental trials.
Thermal comfort will be recorded at 9pm (30 minutes after the scheduled commencement of fan use in the experimental condition), and then every 30 minutes until the participant decides to go to sleep.
Secondary outcome [2] 428979 0
Overnight Thermal Comfort
Timepoint [2] 428979 0
Overnight thermal comfort will be collected during both habituation and experimental trials. Upon waking, participants will be asked to recall their overall thermal comfort overnight.
Secondary outcome [3] 428980 0
Change in core temperature from fan-on time (8:30pm) until fan-off time (7:30am) (11hrs)
Timepoint [3] 428980 0

Gastrointestinal temperature will be continuously recorded during all trials, including habituation and experimental.
The monitoring period in all trials will be from 8:30pm to 7:30am, to coincide with the use of the fan in the experimental trial.
The change in gastrointestinal temperature from baseline (8:30pm) will be analysed every hour from 8:30pm to 7:30am (11 time points)
Secondary outcome [4] 428981 0
Subjective Sleep Quality
Timepoint [4] 428981 0
Subjective sleep quality will be collected during both habituation and experimental trials. In all trials, this will be assessed upon waking.
Secondary outcome [5] 428982 0
Psychomotor vigilance reaction time
Timepoint [5] 428982 0
Psychomotor vigilance will be measured during experimental trials only.
The PVT will be administered at 8AM in all participants, 30 min after the fan is turned off.
Secondary outcome [6] 428983 0
Skin temperature
Timepoint [6] 428983 0
Skin temperature will be measured in all trials, including habituation and experimental trials.
The monitoring period in all trials will be from 8:30pm to 7:30am, to coincide with the use of the fan in the experimental trial.
The mean skin temperature will be analysed hourly between 8:30pm and 7:30am (11 time points)
Secondary outcome [7] 428987 0
Urine Specific Gravity
Timepoint [7] 428987 0
Urine specific gravity will be measured in all trials, including habituation and experimental trials.
A mid-stream sample will be collected upon waking in all trials.
Secondary outcome [8] 428988 0
Overnight whole-body sweat loss
Timepoint [8] 428988 0
Whole body sweat loss will be calculated in all trials, including habituation and experimental trials. This will be calculated by subtracting nude weight at 7:30am from nude weight at 8:30pm, to coincide with the fan use time in the experimental conditions.
Secondary outcome [9] 428989 0
Dehydration
Timepoint [9] 428989 0
Markers of dehydration will be assessed in all trials, including habituation and experimental trials.
In each trial, a blood draw will occur just before 8:30pm, and just after 7:30am, to coincide with the time of fan use during the experimental conditions.
Secondary outcome [10] 434030 0
Sleep latency
Timepoint [10] 434030 0
Sleep latency will be measured in all trials, including habituation and experimental trials.

The Nox A1 will be set to start recording at 8:30pm, and will record data continuously for 11 hours until 7:30am.

During the experimental trials, this will record data for the entire period of fan use.
The same time period will be captured during habituation trials, where participants are sleeping in thermoneutral conditions without a fan.
On each occasion, participants will indicate their own lights out time.
Secondary outcome [11] 434031 0
Wake after sleep onset (WASO)
Timepoint [11] 434031 0
WASO will be measured in all trials, including habituation and experimental trials.

The Nox A1 will be set to start recording at 8:30pm, and will record data continuously for 11 hours until 7:30am.

During the experimental trials, this will record data for the entire period of fan use.
The same time period will be captured during habituation trials, where participants are sleeping in thermoneutral conditions without a fan.
Secondary outcome [12] 434032 0
Sleep efficiency (percent)
Timepoint [12] 434032 0
Sleep efficiency will be measured in all trials, including habituation and experimental trials.

The Nox A1 will be set to start recording at 8:30pm, and will record data continuously for 11 hours until 7:30am.

During the experimental trials, this will record data for the entire period of fan use.
The same time period will be captured during habituation trials, where participants are sleeping in thermoneutral conditions without a fan.
Secondary outcome [13] 434033 0
REM Sleep time (minutes)
Timepoint [13] 434033 0
Rapid eye movement (REM) sleep time will be measured in all trials, including habituation and experimental trials.

The Nox A1 will be set to start recording at 8:30pm, and will record data continuously for 11 hours until 7:30am.

During the experimental trials, this will record data for the entire period of fan use.
The same time period will be captured during habituation trials, where participants are sleeping in thermoneutral conditions without a fan.
Secondary outcome [14] 434034 0
Non-rapid eye movement sleep (NREM) sleep time
Timepoint [14] 434034 0
NREM sleep time will be measured in all trials, including habituation and experimental trials.

The Nox A1 will be set to start recording at 8:30pm, and will record data continuously for 11 hours until 7:30am.

During the experimental trials, this will record data for the entire period of fan use.
The same time period will be captured during habituation trials, where participants are sleeping in thermoneutral conditions without a fan.
Secondary outcome [15] 434035 0
Total arousal count
Timepoint [15] 434035 0
Total arousal count will be measured in all trials, including habituation and experimental trials.

The Nox A1 will be set to start recording at 8:30pm, and will record data continuously for 11 hours until 7:30am.

During the experimental trials, this will record data for the entire period of fan use.
The same time period will be captured during habituation trials, where participants are sleeping in thermoneutral conditions without a fan.
Secondary outcome [16] 434036 0
Total arousal count (REM sleep period)
Timepoint [16] 434036 0
Total arousals during the REM sleep period will be measured in all trials, including habituation and experimental trials.

The Nox A1 will be set to start recording at 8:30pm, and will record data continuously for 11 hours until 7:30am.

During the experimental trials, this will record data for the entire period of fan use.
The same time period will be captured during habituation trials, where participants are sleeping in thermoneutral conditions without a fan.
Secondary outcome [17] 434037 0
Total arousal count (NREM sleep period)
Timepoint [17] 434037 0
Total arousal count during the NREM sleep period will be measured in all trials, including habituation and experimental trials.

The Nox A1 will be set to start recording at 8:30pm, and will record data continuously for 11 hours until 7:30am.

During the experimental trials, this will record data for the entire period of fan use.
The same time period will be captured during habituation trials, where participants are sleeping in thermoneutral conditions without a fan.
Secondary outcome [18] 434043 0
Total Sleep Time
Timepoint [18] 434043 0
Total sleep time will be measured in all trials, including habituation and experimental trials.

The GENEActiv will record data for the entire period of fan use. The same time period will be captured during habituation trials, where participants are sleeping in thermoneutral conditions without a fan.
Secondary outcome [19] 434044 0
Sleep onset latency
Timepoint [19] 434044 0
Sleep onset latency will be measured in all trials, including habituation and experimental trials.

The GENEActiv will record data for the entire period of fan use. The same time period will be captured during habituation trials, where participants are sleeping in thermoneutral conditions without a fan.
Secondary outcome [20] 434045 0
Sleep efficiency
Timepoint [20] 434045 0
Sleep efficiency will be measured in all trials, including habituation and experimental trials.

The GENEActiv will record data for the entire period of fan use. The same time period will be captured during habituation trials, where participants are sleeping in thermoneutral conditions without a fan.
Secondary outcome [21] 434046 0
Wake after sleep onset (WASO)
Timepoint [21] 434046 0
WASO will be measured in all trials, including habituation and experimental trials.

The GENEActiv will record data for the entire period of fan use. The same time period will be captured during habituation trials, where participants are sleeping in thermoneutral conditions without a fan.
Secondary outcome [22] 434047 0
Number of arousals
Timepoint [22] 434047 0
Number of arousals will be measured in all trials, including habituation and experimental trials.

The GENEActiv will record data for the entire period of fan use. The same time period will be captured during habituation trials, where participants are sleeping in thermoneutral conditions without a fan.
Secondary outcome [23] 434066 0
Psychomotor vigilance false starts
Timepoint [23] 434066 0
Psychomotor vigilance will be measured during experimental trials only.

The PVT will be administered at 8AM in all participants, 30 min after the fan is turned off.
Secondary outcome [24] 434067 0
Psychomotor vigilance non-responses
Timepoint [24] 434067 0
Psychomotor vigilance will be measured during experimental trials only.

The PVT will be administered at 8AM in all participants, 30 min after the fan is turned off.
Secondary outcome [25] 434068 0
Working Memory reaction time
Timepoint [25] 434068 0
2-back will be measured during experimental trials only.

The 2-back will be administered at 8:10 AM in all participants, 40 min after the fan is turned off.
Secondary outcome [26] 434069 0
Working memory correct responses
Timepoint [26] 434069 0
2-back will be measured during experimental trials only.

The 2-back will be administered at 8:10 AM in all participants, 40 min after the fan is turned off.
Secondary outcome [27] 434070 0
Working memory false responses
Timepoint [27] 434070 0
2-back will be measured during experimental trials only.

The 2-back will be administered at 8:10 AM in all participants, 40 min after the fan is turned off.
Secondary outcome [28] 434071 0
Inhibitory control reaction time
Timepoint [28] 434071 0
Go/no-go will be measured during experimental trials only.

The Go/no-go will be administered at 8:20 AM in all participants, 50 min after the fan is turned off.
Secondary outcome [29] 434072 0
Inhibitory control false responses
Timepoint [29] 434072 0
Go/no-go will be measured during experimental trials only.

The Go/no-go will be administered at 8:20 AM in all participants, 50 min after the fan is turned off.
Secondary outcome [30] 434078 0
Global cognitive composite score
Timepoint [30] 434078 0
The cognitive tests required for this will begin at 8AM on each experimental day, 30 min after the fan is turned off

Eligibility
Key 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
Minimum age
18 Years
Maximum age
40 Years
Sex
Both males and females
Can healthy volunteers participate?
Yes
Key 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

Study design
Purpose of the study
Prevention
Allocation to intervention
Randomised controlled trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
Allocation is concealed. The randomisation sequence will be generated by a colleague not involved in the study. When a participant is enrolled, the investigator will be contacted to provide the order of experimental conditions.
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
A counterbalanced sequence (fan vs no-fan) will be generated with randomly permuting blocks of 2, 4, 6 and 8. THe randomisation sequence will be stratified by sex. The sequence will be generated using the randomizeBE package in R.
Masking / blinding
Blinded (masking used)
Who is / are masked / blinded?
The people receiving the treatment/s

The people assessing the outcomes
The people analysing the results/data
Intervention assignment
Crossover
Other design features
Phase
Not Applicable
Type of endpoint/s
Efficacy
Statistical methods / analysis
According to the American Academy of Sleep Medicine, the minimal clinically important difference for improvement in sleep time for non-pharmacological treatments is 15 min. Previous work on the use of fans to increase air flow in conditions of 32°C and 80% relative humidity showed an increase in total sleep time of 82 minutes compared to a no fan control condition. Assuming a correlation of 0.7, this provides an effect size of 1.07. Assuming our intervention is half as effective in a hotter environment (an improvement in total sleep time of 40 minutes; standardised effect size of 0.53), a two-tailed alpha of 0.05 and beta of 0.2, we require 30 participants to detect a significant difference between conditions. Power calculations were performed using G*Power version 3.1.9.6.

Data analysis will occur after the completion of data collection, with the statistician blind to condition. The primary outcome is total sleep time (minutes), measured using polysomnography (Nox A1). The effect of fans on total sleep time (dependent variable) will be analysed using a repeated measures ANOVA that employs a repeated factor of Fan” (2 levels Yes and No). The critical alpha will be set at 0.05. No interim analysis is planned.

Recruitment
Recruitment status
Recruiting
Date of first participant enrolment
Anticipated
1/05/2024
Actual
20/05/2024
Date of last participant enrolment
Anticipated
Actual
Date of last data collection
Anticipated
Actual
Sample size
Target
30
Accrual to date
2
Final
Recruitment in Australia
Recruitment state(s)
NSW

Funding & Sponsors
Funding source category [1] 315248 0
Government body
Name [1] 315248 0
National Health and Medical Research Grant under the Ideas Grant Scheme
Country [1] 315248 0
Australia
Primary sponsor type
University
Name
The University of Sydney
Address
Camperdown NSW 2050
Country
Australia
Secondary sponsor category [1] 317279 0
None
Name [1] 317279 0
Address [1] 317279 0
Country [1] 317279 0

Ethics approval
Ethics application status
Approved
Ethics committee name [1] 314168 0
The University of Sydney Human Research Ethics Committee
Ethics committee address [1] 314168 0
Research Integrity & Ethics Administration Research Portfolio Level 3, F23 Administration Building The University of Sydney, NSW, 2006
Ethics committee country [1] 314168 0
Australia
Date submitted for ethics approval [1] 314168 0
23/06/2023
Approval date [1] 314168 0
26/09/2023
Ethics approval number [1] 314168 0
2023/633

Summary
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.

Trial website
Trial related presentations / publications
Public notes

Contacts
Principal investigator
Name 130658 0
Dr Yorgi Mavros
Address 130658 0
Susan Wakil Health Building, The University of Sydney, Western Ave, Camperdown NSW 2050
Country 130658 0
Australia
Phone 130658 0
+61 293519279
Fax 130658 0
Email 130658 0
[email protected]
Contact person for public queries
Name 130659 0
Yorgi Mavros
Address 130659 0
Susan Wakil Health Building, The University of Sydney, Western Ave, Camperdown NSW 2050
Country 130659 0
Australia
Phone 130659 0
+61 293519279
Fax 130659 0
Email 130659 0
[email protected]
Contact person for scientific queries
Name 130660 0
Yorgi Mavros
Address 130660 0
Susan Wakil Health Building, The University of Sydney, Western Ave, Camperdown NSW 2050
Country 130660 0
Australia
Phone 130660 0
+61 293519279
Fax 130660 0
Email 130660 0
[email protected]

Data sharing statement
Will individual participant data (IPD) for this trial be available (including data dictionaries)?
Yes
What data in particular will be shared?
De-identified individual participant data underlying published results only
When will data be available (start and end dates)?
Immediately following publication, no end date
Available to whom?
Case-by-case basis at the discretion of the primary investigator
Available for what types of analyses?
Meta-analysis
How or where can data be obtained?
Access subject to approvals by the primary investigator with a requirement to sign a data access agreement. Email: [email protected]


What supporting documents are/will be available?

Doc. No.TypeCitationLinkEmailOther DetailsAttachment
20977Informed consent form    386900-(Uploaded-02-04-2024-11-06-26)-Study-related document.docx



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