Evaluating a portable device to advance the internal body clock to treat insomnia

During the treatment week of the study, participants in the treatment condition will use the Re-Timer device to administer bright light therapy. Re-Timers are a portable, lightweight, glasses-like device (Re-Timer Pty. Ltd., Adelaide). In the treatment condition, it administers blue-green light (~500 nm) into the participants visual field, via four Light-Emitting Diodes (LEDs) mounted on the lower frame underneath the eyes. When measured at 20mm from the distance of the eye, the light administered is at an intensity of 506 Lux lm/m2and 230 µW/cm2 (high setting). Re-Timer is worn exactly like glasses and positioned so that the light is directly administered into the visual field. Twenty-four participants will be randomly allocated to either the treatment or control condition. For the twelve participants in the treatment condition, Re-Timer will administer blue/green light. A Re-Timer device will be given to each participant to wear in their own homes for 60 minutes every morning during the treatment week (7 days of exposure). As the device must be worn, participants will administer the treatment themselves in their own homes. To evaluate the efficacy of the Re-Timer device, dim light melatonin onset (DLMO) and skin temperature will be measured as a marker of circadian rhythms. Participants will collect their own saliva samples for DLMO and apply iButtons to measure skin temperature. On day 2 of the treatment week, participants were not allowed to consume food after 17:30 hours as some foods interfere with salivary melatonin concentrations. Six hours before habitual bedtime, participants will sit in a dimly lit room (<10 Lux) for 1 hour and start collecting their own saliva samples at half-hourly intervals from 5-hours before participant’s habitual bed until 2- hours after habitual bedtime. Participants were instructed on how to store these samples to return them. During the saliva collection period, participants could watch television and read but will not be allowed to work on a computer or use a mobile device as the emitted light interferes with melatonin secretion. One hour before their habitual bedtime, participants also completed the Stanford Sleepiness Scale. Upon the final Saliva collection for the night, participants could sleep. Additionally, at the same time as the initial saliva collection, participants wore the iButtons until the following morning. On the morning of day 3, participants will awake 20 minutes earlier than their habitual wake-up time and wear the Re-Timer for 60 minutes. During this time the participants completed their sleep diary and the light sensitivity questionnaire. The participant’s day was then unregulated until 1 hour before their habitual bedtime, in which time they completed the Stanford Sleepiness Scale and sat in a dimly lit room (<10 Lux). They were told to go to bed when they are ready. For the next five days, participants repeated the same protocol as on day 3. But, instead of waking up 20 minutes earlier than their habitual wake-up time, they would wake up 20 minutes earlier and earlier than day before. This in combination with Re-Timer will slowly phase advance their circadian rhythm. Upon the eighth night, the protocol DLMO measurement for day two was repeated for comparison. Adherence to Re-Timer usage is ensured via the participant sleep diary and reminder text messages.