PBM Effects on Health and Well-being in Humans

The goal of this clinical study is to assess the effects of different photobiomodulation (PBM) conditions in men and women between 25 and 65 years old with daytime sleepiness/drowsiness and /or mild mood complaints but be otherwise healthy. The main question it aims to answer are:

1. Does PBM significantly affect health and well-being?
2. Are PBM effects wavelength dependent?
3. Are PBM effects pulse dependent?
4. Are the eyes needed to assert an PBM effect or is exposure only to the skin sufficient?
5. What are the cellular, metabolic pathways underlying the systemic effects of PBM.

Participants will have to:

1. Exposed themselves 5 times per week during 2 weeks to the PBM stimuli between 9:30 and 12:30.
2. A week before the baseline measurement, participants will have to start wearing a Fitbit Versa 3, and will have to continuously wear until the end of the study.
3. In the afternoon of the baseline day as well as in the afternoons after 5 and 10 PBM sessions (week 1 and week 2, respectively), participants will have to go to the lab for blood withdraw.
4. In the evening of the baseline day as well as in the evenings after 5 and 10 PBM sessions (week 1 and week 2, respectively), participants will have to collect saliva samples as well as to complete questionnaires.

It will be a double-blind placebo-controlled field study with a between subject comparison.

Five conditions (groups) will be tested:

Dose (J.cm-2) Wavelength (nm) Pulse (Hz,ms) Duty factor Area Cond 1 6.5 850 15, 8 12% Skin + eyes Cond 2 6.5 940 15, 8 12% Skin + eyes Cond 3 6.5 850 100, 1 12% Skin + eyes Cond 4 0 850 15, 8 12% Skin + eyes Cond 5 6.5 850 15, 8 12% Skin

Eligibility Criteria:
Inclusion Criteria:

Healthy, no chronic disease

* Age between 25 - 65 years.
* Suffer from daytime sleepiness/drowsiness and or a mild mood disturbance (ESS \>5 or BDI equal to or higher than 13 but lower than 20, PSQI \> 5)
* Participants will have to have a desk type of work and/or have 3 hours per day between 9:30 am and 12:30 at their office/home in which they could sit in front of the lamp.

Exclusion Criteria:

Depressive mood (BDI -II \> 20)

* Pregnancy
* Menopause symptoms
* Drug use during the last three months known to interfere with sleep, alertness, the biological clock and/or light sensitivity (i.e. regular usage of sleep medication or stimulating substances)
* Use of immune suppressants. High levels of caffeine intake during a day (5 or more cups, according to https://www.voedingscentrum.nl/encyclopedie/cafeine.aspx#blok7, there are no negative effects expected from 4 caffeine products in normal adults)
* High alcohol intake (more than 4 for men and more than 3 for women, drinks per day) for more than 5 days in the past month, including binge drinking and heavy drinking according to https://www.niaaa.nih.gov/publications/brochures-and- fact-sheets/alcohol-facts-and-statistics.
* Participant is not able to refrain from using recreational drugs during the 4 weeks of the study.
* Shift work schedule in the 3 months prior to participation and/or planned during the 2 weeks of the study
* Environmental factors in everyday life that may disturb sleep and cannot be prohibited (e.g. young children, noisy environment)
* Travel over 2 or more time zones in the month prior to participation
* Travel to sunny holiday locations/wintersports 1 month before participation
* Personal plans that prevent them for using the intervention during 2 consecutive weeks