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Trial registered on ANZCTR

Registration number
Ethics application status
Date submitted
Date registered
Date last updated
Date data sharing statement initially provided
Type of registration
Prospectively registered

Titles & IDs
Public title
Light to improve sleep, cognition, mood and day time alertness
Scientific title
Testing light therapy of changing wavelength in adults suffering from sleep disorders to improve sleep quality, day time alertness, sleep wake patterns, mood and cognition.
Secondary ID [1] 297156 0
Nil known
Universal Trial Number (UTN)
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Sleep disturbance 311189 0
Condition category
Condition code
Neurological 309809 309809 0 0
Other neurological disorders

Study type
Description of intervention(s) / exposure
This randomised controlled trial (RCT) is a device based clinical trial, in which the device is the lighting technology installed in the ceiling of the laboratory suite. The computer software which controls the lighting technology is programmed to predetermined settings to deliver 2 different lighting conditions:

- Light therapy (LT): white light (illuminance at 500 lux) with enriched blue and green wavelengths (440-560nm) from wake-up time until 5 hours prior to habitual sleep time, at which point the blue wavelengths are attenuated to yield yellow-enriched light (570-750nm) and the lights are dimmed to 90 lux.

- Control light: white light (500 lux) from wake-up time to 5 hours prior to habitual sleep time, at which point the lights will be dimmed to 90 lux.

All participants on this study must be 50 years or older and have self-reported poor sleep based on the Pittsburgh Sleep Questionnaire (PSQI, global score >5).
Eligible participants will reside for four consecutive days on two separate occasions, at the Woolcock Institute in one of our research laboratory suites. On each occasion, participants will be exposed to either LT (intervention condition) or sham LT (control condition) in a randomised order (randomised crossover trial) with an intervening 2-week washout period at home. Sleep will be studied using high density electroencephalography (hdEEG) and electromyography (EMG) on the third night during each light condition. HdEEG is a new neurobiological measurement tool permitting detailed topographical analysis of brain activity including identifying local sleep intrusions during wakefulness. It allows for neurocognitive phenotyping, identifying new risk markers and evaluating treatment interventions. Melatonin onset will be assessed from saliva samples collected on the third evening prior to sleep. Daytime function will be assessed using standardised computerised neurocognitive tests on the last two days of the laboratory visits. In addition, brain activity will be measured using routine EEG twice during the study in each (intervention or control) condition, while performing cognitive tasks. Overall, the study will allow us to ascertain whether manipulating the spectrum and timing of light exposure can optimise nocturnal sleep, daytime alertness and improve overall quality of life.

The following questionnaires will be used to assess the participants eligibility for the study as well as determine their baseline level of sleepiness, quality of life and sleep disorders:

- Sociodemographic questionnaire: ethnicity and level of education selection, and lifestyle questionnaire.
- Medical History and Medications: medical history and concomitant medication information will be collected by the study coordinator and sleep physician.
- Wechsler Test of Adult Reading (WTAR): a neuropsychological assessment tool that estimates an individual's level of intellectual functioning before the onset of injury or illness. Requires verbal pronunciation of a specific set of words.
- The Epworth Sleepiness Scale (ESS): rating of general sleepiness in the last two weeks.
- Karolinska Sleepiness Scale (KSS): assessment of subjects’ sleepiness over the last 5 minutes.
- Insomnia Severity Index (ISI): rating of insomnia-related sleep problems.
- Pittsburgh Sleep Quality Index (PSQI): assessment rating sleep quality over the past month.
- Horne & Ostberg Morningness-Eveningness Questionnaire: assessment of what time of the day participants are most productive.
- The Multivariate Apnoea Prediction Index (MAPI) Questionnaire: assessment for the presence and frequency of apnoea symptoms over the last month.
- The Short Form (36) Health Survey: a patient-reported survey of patient health.

The following extensive neurocognitive tests will be used to assess improvement in cognition and alertness with the intervention:

- Psychomotor Vigilance Task (PVT): a tool which is used to assess sustained attention via a simple reaction time task. Subjects will be asked to press a button as quickly as possible in response to numbers appearing across the stimulus window on a small box.
- N-Back: a visuospatial test that assesses working memory, encompassing short term memory storage and information processing. During this test, subjects will watch letters appear in different locations on the screen and subjects will try to match those in the same location.
- The Stroop Task: This computerised test requires subjects to respond to a series of words that are displayed in colours (e.g. the word ‘red’ is displayed in blue) and identify the colour of the word or the definition of the word.
- Letter Cancellation Task: This 10-minute test evaluates concentration, attention and visuospatial scanning ability or neglect. Subjects are shown an array of letters and are required to select a specific type of letters from those shown.
- Declarative Memory (Word Pair) Task: a computerised memory test where subjects are required to learn a set of word pairs and recall them at different stages following the learning stage.
- Procedural Memory (Finger Tapping) Task: assessment of the participants ability to memorise procedures. This Motor Sequence Task requires subjects to repeatedly type a 5-element number on a standard computer keyboard with the subjects’ non-dominant hand. The specific number sequence, which must be typed, is always displayed in front of subjects on the computer screen.
- Symbol digit modality test: a cognitive function tests that asks participants to pair specific numbers with given geometric figures.
Intervention code [1] 313421 0
Treatment: Devices
Comparator / control treatment
Control treatment will simply be to repeat the study, but the participants will be exposed to white light. It will be visually like the light therapy condition but there will be no increased blue and green wavelengths during the day. During the evening blue wavelengths will be attenuated but will be present at a higher proportion than the intervention evening light to mimic the average household.
Control group

Primary outcome [1] 318772 0
Sleep quality determined by wake after sleep onset (WASO assessed) from hdEEG.
Timepoint [1] 318772 0
On the third night of each light condition PSG will be measured.
Secondary outcome [1] 365991 0
Slow wave sleep quantity and power, sleep spindle frequency, density and amplitude, sleep onset latency, total sleep time and arousal index (composite outcomes) will all be measured using High Density EEG.
Timepoint [1] 365991 0
On the third night of each light condition PSG will be measured.
Secondary outcome [2] 365992 0
Melatonin production assessed by analysis of saliva sample.
Timepoint [2] 365992 0
The evening after each 3 days of light therapy treatment.
Secondary outcome [3] 365993 0
Core temperature (oral and auditory canal) assessed by digital oral and tympanic thermometers.
Timepoint [3] 365993 0
The morning and afternoon of day 3 of exposure to light therapy.
Secondary outcome [4] 365994 0
Daytime vigilance assessed by psychomotor vigilance task (PVT), Karolinska Sleepiness Scale (KSS) and Karolinska Drowsiness Test (KDT).
Timepoint [4] 365994 0
The morning and afternoon of day 3 of exposure to light therapy.
Secondary outcome [5] 366118 0
Cognition assessed by a battery of neurocognitive tests that include memory tasks (n-back, word pair task, finger tapping task, the Buschke Selective reminding test (SRT), executive function (stroop test), concentration (letter cancelation task).
Timepoint [5] 366118 0
The morning and afternoon of day 3 of exposure to light therapy.
Secondary outcome [6] 366162 0
Skin temperature assessed by a digital skin thermometer.
Timepoint [6] 366162 0
The morning and afternoon of day 3 of exposure to light therapy.
Secondary outcome [7] 380638 0
Mood assessed by the Hospital Anxiety and Depression Scale (HADS).
Timepoint [7] 380638 0
On the third evening during each light condition

Key inclusion criteria
1. Able to give informed written consent
2. Fluent English speaker
3. Older than 50 years without cognititve impairment (based on a Mini Mental State Examination (MMSE) with a score >24)
4. Subjective reported poor sleep quality (Pittsburgh Sleep Quality Index global score or PSQI greater than 5).
5. Insomnia severity index (ISI) less than or equal to 15 indicating no clinically significant or subthreshold insomnia
6. Multivariable apnoea prediction index (MAPI) less than or equal to 0.5 indicating low probability of being diagnosed with obstructive sleep apnoea (OSA) and/or an Apnoea-Hypopnea Index (AHI) of less than or equal to 15 indicating no or mild obstructive sleep apnoea.
Minimum age
50 Years
Maximum age
No limit
Both males and females
Can healthy volunteers participate?
Key exclusion criteria
1. Pregnancy or lactation
2. Circadian rhythm disorders
3. People highly dependent on medical care
4. Shift-workers
5. Recent overseas travel (<1month, >2 time-zones)
6. Major psychiatric illnesses
7. Sleep disorders including obstructive sleep apnoea, restless legs syndrome

Study design
Purpose of the study
Allocation to intervention
Randomised controlled trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
Central randomisation by computer.
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
Simple randomisation using a randomisation table created by computer software by an independent investigator not connected with the study.
Masking / blinding
Blinded (masking used)
Who is / are masked / blinded?
The people receiving the treatment/s
The people administering the treatment/s
The people assessing the outcomes
The people analysing the results/data
Intervention assignment
Other design features
Not Applicable
Type of endpoint(s)
Statistical methods / analysis
In this pilot study, the sample size of n=20 allows for approximately 10% attrition and assumes a medium effect size following treatment. Each dataset will require a different set of statistical analysis. Quantitative EEG (qEEG) measures, hdEEG, performance on neurobehavioural and memory a tasks, and questionnaire responses under the two light exposures will be compared using paired t-tests. Associations between the change in sleep qEEG and performance after each light exposure will be assessed using parametric or nonparametric univariate correlations as appropriate.

Recruitment status
Date of first participant enrolment
Date of last participant enrolment
Date of last data collection
Sample size
Accrual to date
Recruitment in Australia
Recruitment state(s)
Recruitment hospital [1] 12972 0
Woolcock Institute of Medical Research - Glebe
Recruitment postcode(s) [1] 25450 0
2037 - Glebe

Funding & Sponsors
Funding source category [1] 301710 0
Name [1] 301710 0
Impact funding perpetual
Address [1] 301710 0
GPO Box 4171, Sydney, NSW, 2001
Country [1] 301710 0
Primary sponsor type
Woolcock Institute of Medical Research
431 Glebe Point road, Glebe, NSW, 2037
Secondary sponsor category [1] 301439 0
Name [1] 301439 0
Impact funding Perpeptual
Address [1] 301439 0
GPO Box 4171, Sydney, NSW, 2001
Country [1] 301439 0

Ethics approval
Ethics application status
Ethics committee name [1] 302429 0
Sydney Local Health District Ethics Review Commitee (RAPH zone) [EC00113]
Ethics committee address [1] 302429 0
Level 11, KGV Building Missenden Road
Ethics committee country [1] 302429 0
Date submitted for ethics approval [1] 302429 0
Approval date [1] 302429 0
Ethics approval number [1] 302429 0

Brief summary
The daily light and dark cycle is the strongest external time cue for humans to maintain circadian rhythmicity via a specialised endogenous network. Impairment of the circadian rhythm has been shown to occur more commonly with advancing age and diminished health and as such has led to a higher prevalence of sleep disorders in the older population. Nonpharmacological strategies to treat sleep and circadian disruptions have been explored. One of these strategies being explored in this research proposal is the use of light therapy (LT).
Evidence shows that LT can improve sleep consolidation, decrease daytime sleepiness and napping, realign desynchronised circadian rhythms and improve cognition. In fact, it has been shown that short wavelength light increases alertness while longer wavelength light promotes sleep. However, no research has tested LT of varying wavelengths during the day over an extended period and whether timed exposure can lead to a greater level of improvement in sleep and cognition.

The study aims to demonstrate that timed exposure to a LT condition of variable wavelength for 4 days (short wavelength enriched in the day and short wavelength-attenuated in the evening) can improve sleep, mood and cognition as well as reverse melatonin suppression when compared to a control lighting condition (white light). Participants older than 50 years with self-reported poor sleep will reside, on two separate occasions, for 4 consecutive days at the Woolcock Institute in one of our research laboratory suites. Polysomnography, high density and routine electroencephalography tests will be conducted to assess sleep and brain activity and determine the primary endpoint of Wake time After Sleep Onset (WASO). Extensive neurocognitive testing using standardised questionnaires and computerised tests will occur during the study to assess cognition and used as secondary endpoints.

Overall, the study will allow us to ascertain whether manipulating the spectrum and timing of light exposure can optimise nocturnal sleep, daytime alertness and improve overall quality of life.
Trial website

Trial related presentations / publications
Public notes

Principal investigator
Name 90214 0
A/Prof Christopher Gordon
Address 90214 0
Woolcock Institute of Medical Research
431 Glebe Point Road, Glebe, NSW, 2037
Country 90214 0
Phone 90214 0
+61 2 91140499
Fax 90214 0
Email 90214 0
Contact person for public queries
Name 90215 0
A/Prof Christopher Gordon
Address 90215 0
Woolcock Institute of Medical Research
431 Glebe Point Road, Glebe, NSW, 2037
Country 90215 0
Phone 90215 0
+61 2 9114 0499
Fax 90215 0
Email 90215 0
Contact person for scientific queries
Name 90216 0
A/Prof Christopher Gordon
Address 90216 0
Woolcock Institute of Medical Research
431 Glebe Point Road, Glebe, NSW, 2037
Country 90216 0
Phone 90216 0
+61 2 9114 0499
Fax 90216 0
Email 90216 0

Data sharing statement
Will individual participant data (IPD) for this trial be available (including data dictionaries)?
What data in particular will be shared?
Individual participant data underlying published results only
When will data be available (start and end dates)?
Available after main trial publication with no end date determined.
Available to whom?
Only researchers who provide a methodologically sound proposal.
Available for what types of analyses?
any purpose
How or where can data be obtained?
requirement to sign data access agreement. Using Scientific contact information in ANZCTR.
What supporting documents are/will be available?
No other documents available
Summary results
No Results