The definitive answer on what time of day you should shower, according to an expert.

When it comes to keeping clean, you’re either a wake-me-up morning shower person, or someone who wants that clean feeling as they slip into bed at night.

And the debate over which routine is superior has raged since showering every day became the norm. So we decided we wanted to end it, once and for all and ask: is it better to shower in the morning or at night?

To find out, we spoke to Professor Mary-Louise McLaws – an expert in hygiene and infection control at the University of New South Wales.

Listen: Apparently, you’re not meant to soap on your vagina. (Post continues after audio.)

She told us – drum roll – showering before bed is best.

Right now you’ll either be celebrating and perhaps turning to your partner/co-worker/friend and gleefully saying “See!”… or you’re wondering why on earth your morning shower routine isn’t good enough.

Well, Professor McLaws told Mamamia that’s because your end-of-the-day body will dirty your clean sheets. Each night you hop into bed unclean, you add more and more germs. Germs that you then stew in for eight hours.

“You’re putting in dirty feet and a sweaty, odoured body on to your clean sheets. If you want to only shower in the morning, you’ll probably need to wash your pillowcase and your sheets more often,” she says, adding that even if you shower before bed, you should still wash your sheets – along with your towels – once a week.

‘But you don’t understand. I need my morning shower to wake up!’ we hear you saying. Well, if you really don’t think you can part with that, Professor McLaws says you can shower twice a day – though dermatologists do not like you to.

Her solution? “Just have a very quick shower, but don’t use a harsh soap.”

Instead, Professor McLaws recommends washing with a gentle, non-soap-based cleanser, which she also recommends for your nightly shower if you can help it. This is because too much scrubbing with harsh cleansers can damage the outer layer of our skin.

The order you clean your body is important.

Professor McLaws said there were other things to keep in mind while showering. In addition to using a lots less soap than you think you need, the order in which you clean your body is important.

“When people shower, it’s important that they wash their face first – their hands are clean and they haven’t touched their groin.”

Next you should clean your armpits, followed by the rest of your body only if you’re actually sweaty or dirty and then lastly your groin area.

“This is because bacteria lives in the gut, and if it gets into your armpit and you don’t wash your armpit completely clean of this bacteria, it can cause odour. It’s very important to wash your armpits, then your groin and then wash your hands.”

Same goes for shaving.

According to Professor McLaws, it’s also important that if you’re shaving your underarms, legs and bikini line, you do your underarms first.

“There are bacteria that are normally in our groin, most of the time they don’t do any harm. But when you use a razor it does grate the skin and you have microscopic cuts, and if you shave your bikini line and then go to do under your arms, that has the potential of moving bacteria that is still on the razor.”

And that is a recipe for an infection, Professor McLaws says.

Wash your face morning and night, regardless of when you shower.

This is something that most women are doing anyway, but for any fellas reading – or girlfriends or wives who want to help their partner out – Professor McLaws says washing your face each morning and night is important.

And not just if you have acne or any other skin conditions.

“That’s to keep your skin free form sores and small, infected pores,” she says.

“About a third of everyone in Australia carries a bacteria in their nose. It’s called staphylococcus aureus. It doesn’t always stay in our nose, it moves around, a lot of moisture comes out of our nose as we breathe and at night. And that staph can then travel on your skin.”

Again, Professor McLaws recommends using a mild, non-soap cleanser for this.

So there you have it: shower nightly (groin last), wash your face twice daily, and clean your sheets and towels weekly.

How does this stack up against your existing showering routine?