Beds are used primarily for satisfying the Energy need. All beds have these interactions.
Sleep: Although sofas and recliners can build energy, none of them can fulfill maximum energy. All beds fulfill maximum energy with the Sleep interaction. As well, sims remember which beds you tell them to sleep on and will autonomously choose the correct bed after a few nights of repetition.
Relax: Satisfies comfort. This can also lead to two sub-interactions (Day Dream and Read Book) or some object based socials if two sims are using the same bed. If two sims of the appropiate age are using both sides of a double bed, they will autonomously chat with each other, they can also Kiss and WooHoo if you direct them to.
Make Bed: Only happens when sims wake up. Neat sims will make their bed by themselves and will even do so if you cancel the interaction.
Jump: Children can jump on the bed for fun. The need maxs all refer to how much fun this interaction can fulfill.
None of the beds are available on community lots although later expansion packs do make them available.