Black-Out Material

I use plastic room darkenings shades. The kind that roll up to the top. You can find them at Meijer or Walmart for like $7.

I've seen them in catalogs like onestepahead.com that you just put on your curtain rod, but I haven't used any myself.

funny you ask as I just finished sewing some. If you have basic sewing skills it is not hard to attach it to curtains (You could use fusing to depending on what type of blackout material you have) I made sheer curtains into blackout ones. We live across from an industrial area and their flood lights can light up our house. It works great and you can still yse your windows and curtains if they are in this manner. Make sure you rod is a few inches out on either side of the window, that way you will not get very much light from the sides of the window. I hope that this helps.

I hung some of those cheap vinyl roll-up blinds behind the curtains. They are white so they don't show when the white curtains are closed in front of them. The light still comes in just a little bit on the side, but I open the fabric curtains and kind of smoosh them up against the edges to block out the rest of the light.

You can get the honeycombed blackout shades at Home Depot. They are fairly inexpensive, too!

You can buy blackout shades (honeycomb shades with blackout material on the back) that you can install inside the window frame. They won't interfere with your curtains and you can raise them all the way to the top (or if you get the "top down" variety, you can lower them from the top of the window down to whatever height you want, or do both, part down from top/part up from the bottom...). When you are ready for naptime or bedtime, just pull them closed behind your curtain and voila!

We have them in our bedroom because my husband sometimes works nightshifts and sleep during the day. He doesn't need an eye mask or anything with these shades!

http://www.selectblinds.com/cellularshades/34extreme-blac...

I actually bought blackout curtains for my daughters bedroom. they worked wonders. If they aren't opened during the day it is just as dark in her room as it would be at nite. Hopefully this helps

Black out fabric is like what they have in hotels.
Usually it is used as a backing on curtains.

You will notice the place the curtains above the window and past the bottom of the window. They also have it a few it is made to reach slightly on either edge of the window and the curtain connects to can overlap when brought together.
Here is a link that better explains the concept.
http://www.ehow.com/way_###-###-####_homemade-room_darken...

And here is video that shows you how to make them with the fabric you have.
http://video.about.com/apartments/Buy-or-Make-Blackout-Sh...

If you already have the material you could stop at a local craft store and ask for a referral of a local seamstress. They are generally very reasonable and should be able to add the fabric to the back of the curtains you already have so you don't have to fuss with another curtain rod.

I have black out curtains behind my regular curtains on another rod that we hung up. Works great. I work nights and sleep during the day and my room, with my door closed is super dark. There are times I wake up and I have no clue if it's day time or night time!!

I took dark green towels and pinned them to the back side of the curtains in my kid's room. It works great and allows me to open the curtains without any problems.