As part of the Daylight Awareness Week (28th of October - 2nd of November 2024), Prof. Christian Cajochen (Head of the Centre for Chronobiology at the University of Basel in Switzerland) talks about the impact of daylight on our health, with a special focus on sleep. In the first part, we talk about the importance of light for the circadian timing system within our bodies, with melatonin playing an important role. Christian explains why light can have very different effects on our health depending on the time of day of light exposure, and highlights the most important time to see daylight. Christian points out the benefits of daylight particularly for older people. We also critically discuss how difficult it is to study the health effects of daylight without any confounding from other "side-benefits" outdoors. And lastly, we discuss the effects of light on our cardiovascular system (like heart rate and blood pressure) as well as alertness.
More information about the Daylight Awareness Week: https://daylight.academy/daylight-awareness-week-2024/
Chapters:
(0:00:12) Intro & Daylight Awareness Week
(0:02:10) Topics of this episode series
(0:03:33) Introducing Christian Cajochen
(0:08:21) Daylight vs. electric light
(0:13:28) Circadian clocks & melatonin
(0:20:31) Wavelength dependency
(0:23:13) Timing of light matters
(0:30:43) How to study health effects of daylight without confounders?
(0:38:32) Light & Cardiovascular health
(0:45:31) Warm feet to promote sleep
(0:52:14) Light & Blood pressure
(0:56:11) Outro & Teaser to Part 2
Studies that Christian refers to:
The aging clock: circadian rhythms and later life
https://doi.org/10.1172/JCI90328
A Phase Response Curve to Single Bright Light Pulses in Human Subjects
https://doi.org/10.1113/jphysiol.2003.040477
Positive Effect of Daylight Exposure on Nocturnal Urinary Melatonin Excretion in the Elderly: A Cross-Sectional Analysis of the HEIJO-KYO Study
https://doi.org/10.1210/jc.2012-1873
The biological clock tunes the organs of the body: timing by hormones and the autonomic nervous system
https://doi.org/10.1677/joe.0.1770017
Light activates the adrenal gland: Timing of gene expression and glucocorticoid release
Warm feet promote the rapid onset of sleep
https://www.nature.com/articles/43366
Functional link between distal vasodilation and sleep-onset latency?
https://doi.org/10.1152/ajpregu.2000.278.3.R741
Changing color and intensity of LED lighting across the day impacts on circadian melatonin rhythms and sleep in healthy men
https://doi.org/10.1111/jpi.12714
Circadian mechanisms of 24-hour blood pressure regulation and patterning
https://doi.org/10.1016/j.smrv.2016.02.003
Alerting effects of light
https://doi.org/10.1016/j.smrv.2007.07.009
How to contact Christian Cajochen:
Email: Christian.Cajochen@upk.ch
Twitter: @ollen44
LinkeIn: https://www.linkedin.com/in/christian-cajochen-1435258/
