Do you really need a top sheet in bed?

Sometimes I think I'm conflict-averse but then someone says there's no need for a top sheet and suddenly I'm ready for battle.

Call me a traditionalist, but as a Queenslander, I like my top - or flat - piece of linen, to cover me on those (many) hot nights.

Beyond personal preference, we asked experts if there were any benefits to using a top sheet when it came to hygiene, and how often you should clean your sheets.

Who uses a top sheet?

Most of us use top sheets, according to our scientific study (aka Instagram straw poll).

Of 3042 votes on the ABC Lifestyle account, 72 percent said they used one.

Users said a flat sheet helped keep their doona or duvet cleaner for longer, was a good light cover on hot nights, and was a "hygienic" practice.

Those against a top sheet in bed cited reasons including tangling, extra items to wash, and a longer time spent making the bed.

"Pointless," wrote one user.

Our stats are in line with what Kate Croukamp has observed when making beds. She owns a cleaning business in Australia's Gold Coast/Yugambeh language region and is pro-top-sheet for her own bed.

"I see more people with top sheets than not."

A matter of climate

Croukamp believes top sheets came about out of necessity because washing a doona is not always as simple as taking the cover off.

"Back in the day, it was the whole doona or blanket you had to wash. To avoid that, a top sheet came into play."

Croukamp said in cooler parts of Australia, you might see less of a desire for top sheets.

"I lived in the UK and [many] don't do top sheets because it's always cold."

Is a top sheet more hygienic?

Rietie Venter is an associate professor and head of the microbiology laboratory at the University of South Australia.

She doesn't use a top sheet.

"I really don't like them - for non-microbiology reasons. They just get tangled and in the way."

But Venter said there may be a "slight benefit" to using a top sheet.

"It's another layer between you and the duvet.

"It's true sweat and [bacteria] could get through to the duvet itself, but like in my case I just prefer to wash the duvet cover as frequently as I would have washed a sheet."

She said most of the germs living in our beds are normal skin microbiomes that keep us healthy anyway.

"Those things tend not to make you ill unless you are immunocompromised.

"The only thing that is more troublesome is microbiomes like fungi."

Venter said if there is dampness or wetness, such as sweat, in sheets, fungi can grow and make spores, which can spread and make people ill.

"But in general, it's not a problem."

Ashley Franks, a professor of applied and environmental microbiology at La Trobe University in Melbourne, likes a top sheet.

"I prefer the feeling of a sheet on me, rather than being completely open to the air [when it's too hot for a doona]," Franks said.

He said in hot and humid climates, bacteria is more likely to grow in our beds but this isn't a real danger to most people.

Should we wash our doona cover more if we don't use a top sheet?

How often you wash your top sheet or doona cover comes down to climate and other things, like whether you shower at night, said Venter.

"For most people who don't sweat hugely, once a week or every two weeks should be fine."

Franks said what you wear to bed might also affect how often you should wash your sheets. A nude sleeper, as opposed to someone who wears pyjamas, might find their linen needs changing more frequently.

He said your body will usually show signs if your washing frequency is an issue.

"If you get rashes or skin conditions, that will tell you something is going on.

"But a lot of people don't bother [washing their bed linen regularly] and nothing happens. You might be in filth, but it's your own filth."

- ABC