Would a different number of hours affect aging?

[novaprime]

If you where in an alternative environment would a different number of hours affect aging, compared to someone in the regular world.

At first though you'd think likely yes, but then consider that the body has a rythm. This isn't exactly a entirely theoretical question, I know submarines operate on 20hr days.

 

[Ryan_m_b]

Aging is a complex process that I doubt would be affected directly by this, however if you set up an environment with a significant different day/night cycle you could cause circadian rhythm disruptions which would negatively affect health.

 

[jim mcnamara]

I think the "day length" for subs is 18 hours. See below.

Ryan is correct. If you created an isolated 12 hour day environment and put humans in it, there would likely be physiological changes in response to it. Since this regime never occurs naturally, and has never existed for primates or mammals, chances are really good humans would fare poorly.

We are very well adapted to life on Earth with circadian rhythms based on the current day/night cycle. Even so, humans do not fare well with extreme day/night regimes. Example: some people from temperate regions become so-called 'light looney' when day lengths extend to 20+ hours. They become overly euphoric, and tend not to sleep adequately for a while. SAD (seasonal affective disorder) is the reverse problem. Really long nights with short days cause human behaviors to deviate from the norm as well. Often this involves depression. Light therapy is sometimes effective to reverse the changes. SAD has been studied extensively. For example exposure to light mediates production of circadian cycle related hormones like melatonin.

SAD: https://www.nlm.nih.gov/medlineplus/seasonalaffectivedisorder.html

PS: ADA publication http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA306497
stipulates as 6 hour on 12 hour off cycle with no external light for long duration submarine operations. This is based partly on research, partly on naval tradition, and partly on efficiency of operation mandates.