Hanging a hammock chair from the ceiling is only safe if it is supported by a ceiling joist. Plaster and drywall are not strong enough to support the weight of an adult human, and will crack and break if the hammock is hung from them. The hammock chair should be anchored in beams and attached to eye hooks using a drill bit. For people weighing over 200 pounds, a single ceiling joist may not be enough to support the weight, so extra caution should be taken.