Please send feedback if you feel the Fire needs to be dimmer
I just sent an email to Amazon and figured I'd send directions for anyone unsure how to do it (Not that it's hard, but you know, just a little 'nudge' for anyone who wishes they'd either allow the entire device to be made dimmer or just wish the actual Kindle reading app would have an additional slider inside to dim further while reading.
Click on "Your Account"
Toward the bottom, click on "Help"
On the right side of screen click "Contact Us"
Click on "Kindle"
Then choose the Fire
Then from the drop-down click "Kindle Device"
Then from the second drop-down click on the last selection, "Provide Feedback"
Then send an email/call/whatever. I sent an email asking them to add a brightness slider *inside* the Kindle reading app. Maybe if enough people request it, it could happen.