Silly question

Ok, First of all these are the types of question that pop into my head in the middle of the night. Don't ask me why, but it is what is.
Anyway, I have a 70-200 mm f/4 L non-IS that I use pretty much all of the time with the lens hood on. My question is: does the hood prevent some light from reaching the lens and therefore affecting the amount of light needed to take a pic. In other words, if I had the hood off, would I be able to take pictures in somewhat less light?
Thanks for your thoughts.

It does prevent light from hitting the lens, in the way that it prevents lens flare.
However, removing it won't make more light magically appear and help you get that shot.

So your answer is no it doesn't affect it, but it does a little, but not in that way.

If the light source is from the sides (can be top or bottom also) the light hitting the lens at an angle will distort the image (lens flare). The purpose of the hood is to eliminate the chance of flare.

If the light source is behind you or the subject then using the hood or removing it should result in the same picture.

As the others have said. It's not like a filter that cuts the amount of light of your subject / composition from reaching the sensor.

It is supposed to cut down any other light that isn't in your composition that will 'negatively' affect your image such as sunflare or washout.

(I quote 'negatively' as some people may want those effects from time to time).

Thanks everyone for your input. Clarifies things for me.