Seriously, thank god I'm not afraid of the dark! These curtains come THROUGH, and they're also available in 26 colors and three lengths (63", 84", and 95").
While I could have gone for even more sun-blocking power with a longer length (the ones I have are 63"), I didn't want to cover the air conditioner just below the window, and these work perfectly as is. I'm consistently able to sleep soundly well until my wake-up time, no matter how sunny it is outside. As a matter of fact, my bedroom was *so* dark this morning that I had to use my phone's flashlight to navigate around the room so I didn't wake up my still-sleeping boyfriend before I left the house.
I have the curtains in light grey, and I noticed that there are reviews suggesting that some lighter-colored options may not provide as much blackout coverage, so that might be something to keep in mind if you're a big fan of ~extreme~ darkness.
I don't think these curtains particularly provide any significant insulation or blockage against outside noise, as the product description suggests, but they do an A+ job at blocking out the sun, and for $20 a pair, that's pretty damn impressive.