How does light affect our internal clock and influence wakefulness?

[robertjford80]

Photons hit our eyes or bodies which activate a certain hormone which causes us to wake up. Does anyone know if the photons have to hit your eye or your body?

 

[atyy]

http://en.wikipedia.org/wiki/Reticular_activating_system
http://ntp.neuroscience.wisc.edu/resource/Neuro675/675-neurobiology-of-sleep-waking%20I.pdf
http://ntp.neuroscience.wisc.edu/resource/Neuro675/675-neurobiology-of-sleep-waking%20II.pdf
http://tools.medicine.yale.edu/mccormick/www/pubs/gatingMech.pdf

http://en.wikipedia.org/wiki/Melanopsin
http://www.sciencemag.org/content/279/5349/396.abstract (! has this been replicated?)

 

[Monique]

http://www.sciencemag.org/content/279/5349/396.abstract (! has this been replicated?)

Not that I am aware of. There was a time that anti-jetlag devices were sold that were placed in the knee pit, but I'd be interested to know whether they really work. A clue comes from people who are blind, the publications I have seen report that they have free-running circadian periods.

 

[robertjford80]

About blind people, I mean photons hitting your closed eyelids

 

[Monique]

About blind people, I mean photons hitting your closed eyelids

What do you mean? Light still penetrates the eye when the eyelids are closed.

 

[robertjford80]

Blind people have eyes, they just don't work, unless they've been gouged out which is very rare. So what point are you trying to make then with blind people?

 

[Monique]

Think for one second. Your question was: "Does anyone know if the photons have to hit your eye or your body?".

If blind people have problems waking up, do you think their body is important or their eyes? Also, do you think it is having eyes that is important or having visually functional eyes?

 

[robertjford80]

Here's what I originally read, I decided to track it down. This comes from the Harvard Medical Guide to Sleep

light, focused on the back of the eye, can be used to reset the internal clock and treat circadian rhythm disorders such as jet lag

Somehow the first part of the sentence got cut off, so I'll have to look at the original book to see what got cut off but that's at home.