Showering is an important part of an good hygiene routine. Valerii_k/ Shutterstock

It’s a question that’s long been the cause of debate: is it better to shower in the morning or at night?

Morning shower enthusiasts will say this is the obvious winner, as it helps you wake up and start the day fresh. Night shower loyalists, on the other hand, will argue it’s better to “wash the day away” and relax before bed.

But what does the research actually say? As a microbiologist, I can tell you there actually is a clear answer to this question.

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First off, it’s important to stress that showering is an integral part of any good hygiene routine — regardless of when you prefer to have one.

Showering helps us remove dirt and oil from our skin, which can help prevent skin rashes and infections.

Showering also removes sweat, which can quell body odour.

Although many of us think that body odour is caused by sweat, it’s actually produced by bacteria that live on the surface of our skin. Fresh sweat is, in fact, odourless. But skin-dwelling bacteria – specifically staphylococci – use sweat as a direct nutrient source. When they break down the sweat, it releases a sulphur-containing compound called thioalcohols which is behind that pungent BO stench many of us are familiar with.

Day or night?

During the day, your body and hair inevitably collect pollutants and allergens (such as dust and pollen) alongside their usual accumulation of sweat and sebaceous oil. While some of these particles will be retained by your clothes, others will inevitably be transferred to your sheets and pillow cases.

The sweat and oil from you skin will also support the growth of the bacteria that comprise your skin microbiome. These bacteria may then also be transferred from your body onto your sheets.

Showering at night may remove some of the allergens, sweat and oil picked up during the day so less ends up on your bedsheets.

However, even if you’ve freshly showered before bed, you will still sweat during the night – whatever the temperature is. Your skin microbes will then eat the nutrients in that sweat. This means that by the morning, you’ll have both deposited microbes onto your bed sheets and you’ll probably also wake up with some BO.

A night shower can help rinse away the day’s dirt and grime, but you might not smell as fresh the next morning.
leungchopan/ Shutterstock

What particularly negates the cleaning benefits of a night shower is if your bedding is not regularly laundered. The odour causing microbes present in your bed sheets may be transferred while you sleep onto your clean body.

Showering at night also does not stop your skin cells being shed. This means they can potentially become the food source of house dust mites, whose waste can be allergenic. If you don’t regularly wash your sheets, this could lead to a build-up of dead skin cell deposits which will feed more dust mites. The droppings from these dust mites can trigger allergies and exacerbate asthma.

Read more:
Your bed probably isn’t as clean as you think – a microbiologist explains

Morning showers, on the other hand, can help remove dead skin cells as well as any sweat or bacteria you’ve picked up from your bed sheets during the night. This is especially important to do if your sheets weren’t freshly washed when you went to bed.

A morning shower suggests your body will be cleaner of night-acquired skin microbes when putting on fresh clothes. You’ll also start the day with less sweat for odour-producing bacteria to feed on – which will probably help you smell fresher for longer during the day compared to someone who showered at night. As a microbiologist, I am a day shower advocate.

Of course, everyone has their own shower preference. Whatever time you choose, remember that the effectiveness of your shower is influenced by many aspects of your personal hygiene regime – such as how frequently you wash your bed sheets.

So regardless of whether your prefer a morning or evening shower, it’s important to clean your bed linen regularly. You should launder your sheets and pillow cases at least weekly to remove all the sweat, bacteria, dead skin cells and sebaceous oils that have built up on your sheets.

Washing will also remove any fungal spores that might be growing on the bed linen – alongside the nutrient sources these odour producing microbes use to grow.

Primrose Freestone does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.