Hey, all you ‘early birds’ out in the morning sun, running your laps and digging in the garden!
Yeah, you! It’s bad for your health and you are putting your life at risk. You’d be better off sleeping in and doing those things in the afternoon. At least, when its a sunny morning…
Control of skin cancer by the circadian rhythm
Christopher P. Selbya,
William K. Kaufmannb,c,d,
Robert C. Smarte, and
+ Author Affiliations
Departments of aBiochemistry and Biophysics,
cPathology and Laboratory Medicine,
bLineberger Comprehensive Cancer Center, and
dCenter for Environmental Health and Susceptibility, University of North Carolina School of Medicine, Chapel Hill, NC 27599; and
eCell Signaling and Cancer Group, Department of Environmental and Molecular Toxicology, North Carolina State University, Raleigh, NC 27695
Contributed by Aziz Sancar, September 16, 2011 (sent for review August 24, 2011)
Skin cancer is the most common form of cancer in the United States. The main cause of this cancer is DNA damage induced by the UV component of sunlight. In humans and mice, UV damage is removed by the nucleotide excision repair system. Here, we report that a rate-limiting subunit of excision repair, the xeroderma pigmentosum group A (XPA) protein, and the excision repair rate exhibit daily rhythmicity in mouse skin, with a minimum in the morning and a maximum in the afternoon/evening. In parallel with the rhythmicity of repair rate, we find that mice exposed to UV radiation (UVR) at 4:00 AM display a decreased latency and about a fivefold increased multiplicity of skin cancer (invasive squamous cell carcinoma) than mice exposed to UVR at 4:00 PM. We conclude that time of day of exposure to UVR is a contributing factor to its carcinogenicity in mice, and possibly in humans.
Full text here: http://www.pnas.org/content/108/46/18790.full
I always knew it was a good idea to sleep in and those folks up making all the noise in the morning were indulging in silly and risky business ;-)