Making the bedroom really dark for sleeping (on the cheap) – Part 1 – The Windows

With as much as I’ve learned about how terrible artifical lighting is for us (especially at night) and how it messes with our sleep, I almost wish bedrooms were designed without windows. It’s a lot of work to block all the incomming light, even from a street light that isn’t all that bright. I really feel for people who are forced to sleep in the day and have to find ways to totally block out the sun. It’s a challenge. Luckily for many of us, blocking out the light of a street light is challenging enough, but not as bad as blocking out the sun.

So I had gotten my bedroom really dark for sleeping this past summer (you should do it too), but once the leaves fell, we again had a street light putting light into the bedroom.

I already had a light blocking shade up (which you can see bunched up at the top of the window while I’m working), but we would get light from around the edges that shown in.

So I went to walmart and got some white and black posterboard and scotch tape. I got the white for 2 reasons. #1: I read in some cases a black material against glass may cause it to heat up too much in the sun and rarely crack the glass. #2: I didn’t want the outside of the windows to look weird and looking at a black window would look kind of odd.

Note on window films: Yes I consdered window films and read reviews on dozens of them. Most only block some light. I did find one that was supposed to be quite light blocking, however some reported that the black attached to the glass cracked the window in the sun, it was tricky to install right to the very edges of the glass and for a couple windows I think it was $100+. It also was not easily reversible / removalable.

Note on light blocking curtains: I’ve looked at many curtains that claimed to be light blocking, yet it was pretty easy to see in the store they should have been called light reducing. Unless your prepared to spend quite a lot on very heavy curtains, your likely to get light leakage from them. You tend to get light leaking at the top / bottom / sides of most curtains unless very well designed (as I’ve seen just a couple times in nicer hotels). If you have hundreds of dollars or more per window for a great set of truely light blocking curtains, go for it.


WIth the white paper on it, it looks mostly like a shade pulled down unless you study it closely. The white poster board alone does NOT do a good job blocking light at all and even the light on my phones flashlight was bright enough from the outside of the window to light up the window in the bedroom.

I measured and cut the poster board carefully (use a yardstick, draw a line, cut carefully, so the window can still open and close if needed (which is relevant in the summer, once the leaves are back, we can have the window open a bit with very little light entry. (the posterboard covers past the glass onto the window, but not onto the frame.) In addition to allowing your window to still open for air, you shouldn’t block a egress if there happens to ever be an emergency.

I have vinyl windows in this room as many homes do now. Use the tape at your own risk. I have little fear myself of it affecting vinyl, if you have wood, you may damage the finish with tape. Use your own judgement as to what is safe for the finish on your windows!

Once the black layer was on, I tested it with a very bright flashlight outside and I can see little bits of light at the edges, so I expect to see a little bit of light at the edges in the day, but I’m not sleeping in the day, so if a tiny amount comes in when the sun is up, that doesn’t concern me much.

If I was going to be sleeping during the day OR if I found those tiny cracks bother me in the early morning, I will cover the edges with electrical tape. The electrical tape was not my first choice, as it tends to leave more residue if you use a good tape that sticks well like 3M Super 33.

Update: It was pitch black all night, but once the sun was up, I could see a hint of light from the window even with the shade down. I am going to use some more tape and maybe put on a bit of electrical tape, but it basically served it purpose very well.

I want it to be dark dark dark at night for sleep. I think the white poster board is about .33 cents and the black was about .70 cents. It took 2 of each to do one window, so right about $2 to cover both windows. I used about $2 worth of scotch tape as well.

So bottom line, I have about $4 into a window to make it pitch black at night and very dark in the day even if it’s not total perfect darkness with the sun out, but think for those that need to sleep in the day, some electrical tape covering the edges will do the trick.

It took about a hour to cut carefully and put both layers up and test with 2 people.

Happy Sleeping!

p.s. Have a different idea to get your room very dark for sleep? Leave a comment on the blog.

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