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Trial registered on ANZCTR

Registration number
Ethics application status
Date submitted
Date registered
Date last updated
Type of registration
Retrospectively registered

Titles & IDs
Public title
The effect of selective serotonin reuptake inhibitors (SSRIs) on the circadian light response
Scientific title
The effect of a single dose of Citalopram compared to placebo on the circadian systems response to light in healthy adults.
Secondary ID [1] 285011 0
Universal Trial Number (UTN)
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Major Depressive Disorder (MDD) 292524 0
Condition category
Condition code
Mental Health 292827 292827 0 0

Study type
Description of intervention(s) / exposure
Participants will be asked to attend 4 test sessions of ~5 hours each, with ~one week between each session. Each session commences ~4 hours before the participants' habitual bedtime, concluding 1 hour after.

The first two sessions will be dim-light exposures (<1 lux), with citalopram 30mg being administered on the first evening, and placebo on the second. The first evening serves to confirm that citalopram 30mg does not influence absolute levels of melatonin, which would impede our ability to measure the suppression of melatonin during the following light exposures. The second night serves as a dark-control for subsequent light exposures.

The final two nights are light exposures (~100 lux) with participants being randomised to receive either citalopram 30mg, or placebo, first. Each participant will be exposed to both conditions.

A single capsule of citalopram 30mg (or matched placebo) will be administered in the laboratory ~4 hours prior to each participants' bedtime according to their sleep-wake schedule. This takes place during all in lab sessions.
Intervention code [1] 289845 0
Treatment: Drugs
Comparator / control treatment
A single Avicel powder filled capsule will be administered in the laboratory ~4 hours prior to each participants' bedtime according to their sleep-wake schedule during each of their four in-lab test sessions. The study is repeated-measures, therefore all participants will undergo a two dark controls (one with placebo, one with citalopram 30mg) and two light exposures (one with active medication and one with placebo).
Control group

Primary outcome [1] 292693 0
Salivary melatonin levels
Timepoint [1] 292693 0
Saliva samples are taken every ~60 minutes with administration, and finishing 5 hours after administration.
Primary outcome [2] 292694 0
Alertness Testing: Objective and Subjective.

Objective alertness is assessed via an auditory psychomotor vigilance task.

Subjective alertness is assessed every 60 minutes using the Karolinska Sleepiness Scale
Timepoint [2] 292694 0
Test sessions will last for a total of ~5 hours in duration. Four test sessions are included in the protocol: two dark controls and two light exposures where either Citalopram 30mg or Placebo are administered on each occasion (active dark, placebo dark, active light, placebo light).

Objective alertness is assessed bi-hourly beginning 2 hour post administration, and subjective alertness is assessed hourly beginning immediately before administration.
Secondary outcome [1] 309511 0
Timepoint [1] 309511 0

Key inclusion criteria
Healthy Caucasian males and females
Minimum age
18 Years
Maximum age
40 Years
Both males and females
Can healthy volunteers participate?
Key exclusion criteria
- Any history of psychiatric illness or use of psychiatric medication
- Current sleep disorders or erratic/unusual sleep patterns
- Recent or excessive illicit drug use
- Current use of any prescription medication
- Colourblindness
- Recent surgery involving a full anaesthetic
- Any night shift within the past 3 months
- Any travel outside of the current time zone within the last 3 months
- BMI less than 18 or greater than 30
- Epworth Sleepiness Scale score greater than 10
- Beck Depression Inventory score greater than 13
- Use of hormonal contraception
- Abnormal menstrual cycle (<21 days or >35 days in length or irregular/unpredictable)

Study design
Purpose of the study
Allocation to intervention
Randomised controlled trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
Each participant will take part in all conditions, with the order of the light exposures being randomised.

The pharmacist dispensing the medication is responsible for allocating the specific order or administration and this will remain blinded to the researchers until testing has been completed, and individual level analysis has been conducted. A-B categorisation will be provided once individual analysis is complete, so that group level analysis can be completed before researchers will be unblinded.
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
The pharmacist responsible for dispensing the medication and matched placebos (Monash University Campus Pharmacy) generated a randomisation table for the light exposure allocations.

Dark controls were conducted in the same order for all participants.
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
Phase 4
Type of endpoint(s)
Statistical methods / analysis

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 postcode(s) [1] 17979 0
3168 - Notting Hill

Funding & Sponsors
Funding source category [1] 289623 0
Self funded/Unfunded
Name [1] 289623 0
Dr. Sean Cain
Address [1] 289623 0
School of Psychological Sciences - Building 17
Monash University Clayton Campus
Wellington road
Victoria, 3800
Country [1] 289623 0
Primary sponsor type
Monash University
Monash University - Clayton Campus
Wellington Road
Clayton, Victoria, 3800
Secondary sponsor category [1] 288311 0
Name [1] 288311 0
Dr. Sean Cain
Address [1] 288311 0
School of Psychological Sciences - Building 17
Monash University Clayton Campus
Wellington road
Victoria, 3800
Country [1] 288311 0

Ethics approval
Ethics application status
Ethics committee name [1] 291365 0
Monash University Human Research Ethics Committee
Ethics committee address [1] 291365 0
Monash University
Level 1, Building 3e, Clayton Campus
Wellington Rd
Clayton VIC 3800, Australia
Ethics committee country [1] 291365 0
Date submitted for ethics approval [1] 291365 0
Approval date [1] 291365 0
Ethics approval number [1] 291365 0
CF14/1244 - 2014000506

Brief summary
This study aims to examine the effect Citalopram (a common SSRI medication) has on the body's response to light exposure at night. It is hypothesised that as compared to placebo trials, administration of Citalopram will will result in an altered response to night time light exposure.
Trial website
Trial related presentations / publications
Public notes

Principal investigator
Name 50042 0
Dr Sean Cain
Address 50042 0
School of Psychological Sciences - Building 17
Monash University,
Clayton, VIC, 3800
Country 50042 0
Phone 50042 0
+61, 03, 99051194
Fax 50042 0
+61, 03, 99053948
Email 50042 0
Contact person for public queries
Name 50043 0
Dr Sean Cain
Address 50043 0
School of Psychological Sciences - Building 17
Monash University,
Clayton, VIC, 3800
Country 50043 0
Phone 50043 0
+61, 03, 99051194
Fax 50043 0
+61, 03, 99053948
Email 50043 0
Contact person for scientific queries
Name 50044 0
Dr Sean Cain
Address 50044 0
School of Psychological Sciences - Building 17
Monash University,
Clayton, VIC, 3800
Country 50044 0
Phone 50044 0
+61, 03, 99051194
Fax 50044 0
+61, 03, 99053948
Email 50044 0

No information has been provided regarding IPD availability
Summary results
Have study results been published in a peer-reviewed journal?
Other publications
Have study results been made publicly available in another format?
Results – basic reporting
Results – plain English summary