Daylight viewing

Exposure to natural light early in the morning is vital in supporting your circadian rhythm. Circadian rhythm is responsible for the quality of your sleep and even mood.

Complete this task to charge your body with energy for the whole day. Early in the morning, spend 10–15 min. outside in the morning light when it's sunny and 30 min. or more when it is cloudy.

Receiving sunlight through a window is 50 times less effective compared to when being in the open air. Window glass filters out most blue light wavelengths essential in stimulating the eyes and sending a wake-up signal to your body.

On a cloudy day, you should spend twice as much time outside as on a sunny day. Yet, don't be mistaken - it doesn't mean cloudy days are less beneficial - there are still a lot of much-needed photons coming through the clouds.

Remember, even though we are talking about the light that hits your eyes, not your skin, never look at the sun directly.

Impact

Every cell in the human body has a 24-hour clock regulated by genetic and cellular mechanisms. The rising and setting sun is the main factor letting our body know what time of the day it is. This information is perceived by neurons called melanopsin ganglion cells in the eye. They are activated by particular wavelengths of light produced by low solar angles when the sun rises and sets. These melanopsin ganglion cells send a nerve impulse to other neurons responsible for organizing the schedule of your body's cellular processes. 

This process has two highly beneficial effects on your circadian rhythm:

• it triggers the release of cortisol - a stress hormone that helps to wake your system up and is crucial in the mornings. Moreover, cortisol enhances the immune system, which protects you against various infections;
• it sets off a special timer in your body that, after 16 hours, sends a signal to your brain to start releasing melatonin -  a hormone responsible for helping the body to fall asleep.

Berson, D. M., Dunn, F. A., & Takao, M. (2002). Phototransduction by retinal ganglion cells that set the circadian clock. Science (New York, N.Y.), 295(5557), 1070–1073. https://doi.org/10.1126/science.1067262

Brown, T. M., Brainard, G. C., Cajochen, C., Czeisler, C. A., Hanifin, J. P., Lockley, S. W., Lucas, R. J., Münch, M., O'Hagan, J. B., Peirson, S. N., Price, L. L. A., Roenneberg, T., Schlangen, L. J. M., Skene, D. J., Spitschan, M., Vetter, C., Zee, P. C., & Wright, K. P., Jr (2022). Recommendations for daytime, evening, and nighttime indoor light exposure to best support physiology, sleep, and wakefulness in healthy adults. PLoS biology, 20(3), e3001571. https://doi.org/10.1371/journal.pbio.3001571