This is what sleeping with a fan on all night does to your body

As the mercury tips 35°C in parts of the country this week, those of us without the luxury of aircon are clinging to our fans for respite.

For many, the only way to get a decent night’s sleep is to leave one whirring away by the bed until morning in the hope of getting a decent night’s sleep.

But while a fan can make your sweltering bedroom feel far more bearable, experts say sleeping with it on isn’t without its downsides.

From triggering allergies to drying out your skin, here’s what this overnight airflow does to your body – and whether your heatwave saviour actually does you more harm than good come bedtime.

Allergies and asthma

Dr Hana Patel, NHS GP and resident sleep expert at Time4Sleep, tells Metro: ‘Those who experience allergies, especially allergies to dust or hayfever, may find that their symptoms are agitated by sleeping with a fan.

‘This is because the fan will circulate allergens around the room, increasing the likelihood of them being breathed in, or coming into contact with your skin.’

The most obvious sign of this is waking up after a night of sleeping by the fan with symptoms like a sore throat, itching or sneezing.

Similarly, the way this appliance can stir up any dust mites, spores or pollen in your room can also make asthma worse — in which case, Dr Patel says ‘it may be a good idea to avoid sleeping with a fan.’

‘You are likely to find that the fan will cause more issues than benefits, due to it inflaming your medical condition,’ she says. ‘This is especially the case for children.’

Congestion

Waking up feeling bunged up as if you have a winter cold, despite the summer climes?

According to sleep therapist Natalie Pennicotte-Collier, that’s likely down to your trusty cooling device as well.

The resident sleep expert at MattressNextDay tells Metro: ‘A fan running all night progressively dries the mucosal membranes lining your nose, throat and upper airways. Your body responds by producing more mucus.

Muscle pain

‘If the fan is close to you, you may also find that the consistent cold air leads to your muscles tightening as you sleep, causing you to feel aches when you wake up,’ explains Dr Patel.

As well as cramping and pain, pre-existing issues may also be exacerbated.

Dry eyes, mouth and skin

When it comes to skin, Dr Patel likens the effect of sleeping with a fan on to those of a long-haul flight, advising: ‘The key is to moisturise before and after bed to prevent irritation.’

According to Tina Patel, contact lens optician at Feel Good Contacts, eyes can feel dry, gritty or irritated too, ‘especially if it’s blowing directly towards your face.’

‘This effect is often worse in already warm, dry environments, or for those with sensitive eyes,’ she continues.

‘For contact lens wearers who experience dry or irritated eyes, applying eye drops and switching to glasses in the evening may help reduce irritation overnight.’

As a result of all this, your sleep can then end up suffering, with Natalie warning: ‘Many of the clients who come to me struggling with early morning waking, convinced it is stress or anxiety, are actually experiencing the overnight effect of airway dryness from fan exposure.’