The question opens up a can of worms it seems to me. Pet dogs often want to sleep with their owner on their bed. The reason is that they don’t develop past the puppy stage as they look upon their owners as pseudo-parents. As parents they want to curl up next to them. The dog will want to curl up next to the parent either man or woman with whom they are closest emotionally. Of course, it can put a strain on the marital relationship. However, even if a dog is kept off the bed it will still want to sleep as close as possible to his or her ‘pack’ as in the wild, after a wolf has left the nest, they prefer to sleep reasonably close to one another.
It is only pack outcasts who would sleep a long distance from their group. If a dog is shut out of the human bedroom they might feel like an outcast from their adopted pack. If there are other dogs in the household, they can sleep next to them but if they are a solitary pet dog living with a family, they might find it hard to understand why they been shunned at bed time.
The answer, then, is that in some ways it is cruel to stop your dog sleeping on your bed with you at night. It is natural for them to want to sleep with you and to stop naturalness is unpleasant for the animal. A compromise is probably the most common solution with the dog sleeping close by but not on the bed.
I mentioned a can of worms at the beginning because some experts including veterinarians state that dogs should not sleep on your bed as it may be harmful to your health. Dogs are harbingers of potential diseases some experts say. For example, parasites can jump from a dog to their owner. And there are zoonotic diseases which are those that can be transferred from animal to human and vice versa. So, there’s a potential hazard there but there’s a potential health hazard in sleeping with a human. Humans are harbingers of disease just as much as animals. The human is a human-animal in any case. I don’t get this argument.
And to counteract that argument, there are 13 scientifically proven reasons why sleeping with your dog can be beneficial. It helps to reduce depression, promotes Theta brainwaves, increases a sense of security, eases insomnia, maximises comfort, decreases loneliness (when living alone), improve sleep quality and reduce stress! Pow. ?.
So, it is a balancing act it seems to me between the emotional benefits both to humans and dogs of sleeping together, set against the potential transference of diseases from animal to person. Note: Zoonotic diseases are relatively rare which diminishes this potential hazard. And a good owner can eliminate ectoparasites from their dog with good caregiving.
The answer is going to depend upon how risk-adverse the dog owner is. If they are risk-averse they might prioritise the prevention of possible disease transference whereas if they are not risk-averse they can ignore that and go for the benefits as listed above. More importantly we have to look at the obligations of the owner to deliver to their dog companion the best possible life and environment. Under that obligation there is a demand to allow a dog to sleep on their bed at night as it is humans who have created this owner-to-puppy relationship. I would argue that there is a moral obligation under these circumstances to give a dog what they want and need.