Dogs bark, however if they are barking constantly, there is likely to be a cause.
Do not leave your dog alone for long periods, particularly if this causes it to bark. Ensure it is well and exercised before you leave it.
Some dogs like a radio for company, or get a friend or neighbour to pop in. If your dog continues to bark, consider training.
As cats can wail and fight, they can be difficult to manage, however if a neighbour complains about your cat at least try and keep it in at night.
If you have a caged bird that likes to sing and squawk, ensure it's kept where it will least disturb neighbours, particularly at night.
Some caged pets, such as hamsters, tend to be more active at night -chewing and rattling their cages. Consider carefully where and how such pets are housed.