Naked Science Forum

General Science => General Science => Topic started by: Seany on 26/03/2008 22:56:19

Title: Sometimes after you wake up, why can't you look at bright things?
Post by: Seany on 26/03/2008 22:56:19

It's only sometimes, but you can't look at the TV or anything.. Why is this?

Title: Sometimes after you wake up, why can't you look at bright things?
Post by: Karen W. on 27/03/2008 01:51:23

Your eyes have adjusted to the darkness and I imagine that for the light to shine in them after such a break from the light that it must seem glaring... I am not sure why though . I wonder if it has to do with the retina of your ye and perhaps dilation and such... perhaps dilation does something to our eyes... and all the sand and film on our eyes from sleep!

Title: Sometimes after you wake up, why can't you look at bright things?
Post by: science_guy on 27/03/2008 01:59:38

the wider your pupil is opened, the more light is exposed to your eye.  The eye can only take so much light, so over-exposure can possibly go to the point of pain if you look at shiny objects

Title: Sometimes after you wake up, why can't you look at bright things?
Post by: Karen W. on 27/03/2008 02:04:38

So it is the point of dilation? interesting.. does that mean upon waking your eyes ade more dilated then once fully awake..?

Title: Sometimes after you wake up, why can't you look at bright things?
Post by: MayoFlyFarmer on 27/03/2008 04:12:04

yes, when you are in a dark room for a period of time or have your eyes shut (both are true when sleeping) your pupils dialate to try to take in as much light as possible so that you can see in the darkness if needed.  A sudden bright light doesn't allow your pupils to contract and that much light entering your eyes causes pain until the pupils can contract.
The opposite phenomenon occurs when you turn the light off.  Your pupils are small when the light is on.  If it suddenly gets turned off you seem to be in pitch black because so little light is being let in.  After being in the dark for a few minutes your eyes "adjust to the dark" aand you can see quite a bit better.  What actually happened is your pupils dialating to let in as much of the available light in the room as possible.

Title: Sometimes after you wake up, why can't you look at bright things?
Post by: DoctorBeaver on 27/03/2008 07:52:24

In my case, it's the result of too much beer the night before  [xx(]

Title: Sometimes after you wake up, why can't you look at bright things?
Post by: Seany on 27/03/2008 10:34:20

LOL DoctorBeaver [;D]

Thanks Mayo.. Sometimes I can't do anything for like 5-10 minutes!
So if we were to be in the dark for like a month or something.. Would our eyes be able to see in the dark better??

Title: Sometimes after you wake up, why can't you look at bright things?
Post by: Karen W. on 27/03/2008 13:47:39

I bet they would...

You know that brings me to eye exams.. when they dilate your eyes the light hurts your eyes and can damage them unless you wear those lovely wrap around sun shades! I forgot about that...

Title: Sometimes after you wake up, why can't you look at bright things?
Post by: Bored chemist on 27/03/2008 19:32:59

"So if we were to be in the dark for like a month or something.. Would our eyes be able to see in the dark better??"
I think the eye is fully dark adapted in less than an hour.