It is legal to sleep in your car in Arkansas.
While it's legal to sleep in your car in Arkansas, you can only sleep in your car in Arkansas on public property or someone's property that gives you permission.
You can also legally sleep in your car in national forests in Arkansas, if you're dispersed camping on public lands that are managed by the U.S. Forest Service, like the Ouachita National Forest and Ozark St. Francis National Forests.
It's also legal and permitted for you to sleep in your car or vehicle at rest areas for sleep and rest, as state law only prohibits "camping" on public highway lands and not resting in a vehicle.
It can also be illegal to sleep in your car in private parking lots of businesses unless you have permission from the owner.
And many cities in Arkansas also have city ordinances which prohibit sleeping in a car or vehicle on public streets and property between certain hours like 9:00 PM and 6:00 AM.
Even if it's legal in one city, it might be illegal in another city, so you should always check any local ordinances before sleeping in your car.
If there are no parking signs or no overnight parking, then you should not park there or sleep there as you might be fined or asked to move.
And don't camp and only sleep, camping involves setting up a tent or campfire or cooking meals etc.
And avoid making any scenes by keeping any of your belongings out of public view and not making noise.