Hanging a hammock indoors

My kid wants to use their hammock indoors.
My plan is to double up two by sixes over top of the attic
joists and though bolt them with a  1/2" eye bolt.
To maximize the ability to adjust the length of the hammock independent of the height, I thought I would borrow from the Turtledog DIY hammock  stand and suspend a length of top rail from the eye bolts sort of like in the picture below.

It should work. Do NOT drill a 1/2 hole through the ceiling joists, but add a block next to them to run the hole through.  Put 14 1/2 blocks between the joists at the bottom to keep them from twisting.

There are lots of options depending if you are going with or across the joists.

Playground swing hangers may be the cheapest way to get long bolts.

That's for the reply!
Yeah,  even the true 2x lumber my old house is built of won't hold well with a 1/2" hole in it.
Excellent point about the blocking.
Do you think I need a piece of lumber between the eye and the ceiling?

The easiest would be a 2x6 against the ceiling, screwed to the joists, and the double above and blocks where the eye bolts go. Then you wouldn't need all the blocking between the joists.

Not the info you asked for, but since I'm laying in my hammock in my bedroom right now, I figured I'd chime in.

First off, getting rid of my bed was the best thing I ever did for my sleep.  I never toss and turn now, I can wash my "bed" in the washing machine (as opposed to a bed that is a big nasty sponge of dirt that never really can be cleaned).  My back has never felt better, and I wake up without any aches compared to laying on a bed.  
Also, it frees up a ton of space, not that I use or need the space.  
Of course I sleep alone, so there's that, lol.  Sometimes my dogs jump in with me.  :)

To hang mine I just used two 3/8" X 3" eye lag screws screwed into the wall studs.  I've heard that it can bow the walls out, but I strategically hung mine knowing that there was reinforcement behind the wall that would prevent that.

Again, one of the best investments I've ever made for sleep health, and overall body health.  I love it.   So simple.

Quick edit, been sleeping in a hammock every night for the last nine months or so.

Carry on...

I'm also a hammock-sleeper. But mine is held by a steel hammock-frame. I don't know if it's worth the $80 or so for what you're using it for, but I will vouch for these frames. The one I used was bought when I was about 16, which makes it around (redacted) years old.

It squeaked a lot when I first got it, but I figured out how to fix that. The squeaking was coming from where the hook at each end attached to the frame. I took an old shirt from the rag bin and used it to pad the hooks. No more squeak!

I will say, it's best if you're at least a "conscious-turner" if you plan to sleep in these often. Rolling over without falling out takes practice. And I shudder to think what would happen to a sleep-walker!