Beneficial Effects of Daytime Light Exposure and Physical Activity on the Human Circadian Clock and Sleep

Participants stay in the lab with light mimicking usual office lighting. On days 8, 15, and 22, participants start the experimental protocol 5 hours before HBT: questionnaires, behavioural responsiveness (assessed by PVT), saliva samples for melatonin measurements (until HBT and two more following awakening the next day). Participants will go to bed at HBT and get up 8h later in the morning. Their sleep will be assessed with PSG recordings.

Participants spend the same time outdoors in natural daylight. On days 8, 15, and 22, participants start the experimental protocol 5 hours before HBT: questionnaires, behavioural responsiveness (assessed by PVT), saliva samples for melatonin measurements (until HBT and two more following awakening the next day). Participants will go to bed at HBT and get up 8h later in the morning. Their sleep will be assessed with PSG recordings.

Participants spend the same time outdoors in natural daylight wearing tinted glasses that filter out short-wavelength light proportions. On days 8, 15, and 22, participants start the experimental protocol 5 hours before HBT: questionnaires, behavioural responsiveness (assessed by PVT), saliva samples for melatonin measurements (until HBT and two more following awakening the next day). Participants will go to bed at HBT and get up 8h later in the morning. Their sleep will be assessed with PSG recordings.