There's nothing quite like the company of a pet.
They bring comfort and security, so it's unsurprising that half of pet owners let animals sleep in their beds.
But when Rufus's butt is on your pillow and an inch from your face, or Fluffy's grooming you with her tongue from head to toe, you'd be forgiven for wondering if it was damaging to your health or the cause of troubling behaviour.
The quick, cuddly truth is there are several benefits to sleeping with your doggo or pussycat — but depending on the circumstances, there are risks you might like to consider and mitigate.
Why we sleep with our pets
We've been doing it for ages
Human-animal co-sleeping is not new.
Australian study Should we let sleeping dogs lie… with us? says it has been widely recorded in ethnographies of Indigenous Australians.
"This practice is implicated in the common Australian expression 'three-dog night': the colder the night, the more dogs are needed to keep warm."
These days a dog in the bed is less about keeping warm and more about seeing them as valuable members of the family, says animal behaviourist Kate Mornement.
Our pets love it, and we do too
Cats are the most frequent bed visitors, research shows, closely followed by dogs — most commonly smaller breeds.
Our pets like to be in bed with us because it's warm, cosy and they associate that area with positive things like affection and company, says Dr Mornement.
"It's also high up so gives them a better view of the house," she says, noting cats in multi-pet households like to see when other animals are approaching.
For people, our close bonds with pets and the feelings of security and protection they provide are the main reasons we let them on the bed.
The risks and how to mitigate them
Your health
Cats and dogs carry various bacteria and parasites — some of which can be transferred to humans, according to veterinary health expert Jane Heller.
Staphylococcus (skin infections) and parasite diseases like round worms are some example health hazards associated with close contact between humans and pets.
But those risks are low, particularly if the animals are kept clean and have routine vet checks.
And the risks aren't that different to those associated with sharing a bed with another human, Dr Heller says.
"If that human is unwell, or carrying bacteria or a parasite, you won't necessarily get that bug, but the risk is greater than if you were not in such close contact."
Allergies can also be accentuated by having pets in the bed.
One simple way to mitigate these, Dr Heller says, is to train the animal to sleep at the end of the bed on a separate blanket.
"Anyone who has slept in a bed with an animal will have at some stage woken up with their bottom in their face," she says, adding that can increase risk.
Dr Heller says if a person has reduced immunocompetence (when the immune system isn't functioning at full capacity, such as when you are unwell or undergoing medical treatment), "making a choice not to sleep with your pet is sensible".
That can include pregnant women, but for anyone concerned about toxoplasmosis specifically, Dr Heller says that is more likely to transfer from changing kitty litter (in which case women should wear gloves or have someone else do it).
Your quality of sleep
Because dogs are active for about 20 per cent of the night, co-sleeping can cause "relatively mild reductions in overall sleep quality" for humans, a small Australian study found.
Sleep disruption could also be due to mismatches between human, dog and cat core temperatures.
But the disadvantages of human-animal co-sleeping are "small" compared to the social support and increased feelings of security it brings, US researchers have found.
Some pets may be even more disruptive to our sleep when not in the bed — for example, when scratching at doors or barking outside.
Your relationship with the pet
If you're worried about whether letting your pet sleep on your bed will confuse them when it comes to who's boss, you can put that fear aside.
"Being on the bed has nothing to do with being the pack leader or dominant. They just want to be there because it's comfy," Dr Mornement says.
The idea that dogs perceive themselves higher in the pack hierarchy than you is based on dominance theory which has been debunked.
That said, if a dog is showing aggression on the bed, it could be a sign of resource guarding (protecting something they care about).
Having your dog in the bed can increase their risk of separation anxiety, because they are used to being with their owner all the time.
Your relationship with bae
In her consultancy work, Dr Mornement says if there is a disagreement between couples about the pet being in the bed, it's usually men who are unhappy about it.
"It really depends on the person's past experiences with pets," she says, adding some people haven't had close bonds with animals growing up.
Intimacy can also be difficult if the pet isn't sure why they are allowed on the bed sometimes, and not others.
Dr Mornement recently helped a couple with an elderly dog who was causing problems when they were trying to be intimate.
The dog had "separation anxiety" when being shut out of the bedroom, she says.
At the end of the day — it's OK
Ultimately, sleeping with your pet has psychological, social and cultural benefits, and low health and behavioural risks — most of which can be mitigated with care and training.
"We share a real closeness and very strong bond with our pets, that's why we've allowed them to come into our beds," Dr Mornement says.