For some reason, me and my four-year-old son have been hit hardest, which is frustrating, because we've always been the healthiest.
What's most baffling is the fact that the symptoms clear up as soon as we're out in the fresh air, and then return when we get home.
I didn't put two and two together until I read a report from Allergy UK. According to the charity, at least 12 million people are allergic to their own home, suffering from an out of season hay fever called Perennial Allergic Rhinitis.
Bingo! This is what has been afflicting my family. But why all of a sudden? Then I thought back to when we turned our radiators on for the first time. The hot, damp air must have created perfect breeding conditions for an explosion of dust mites and mould. And the reason my youngest son and I have suffered most is because, although we sleep on different floors, our beds are in the same corner of the house where damp mould spores have spread up the wall.
In fact, I went to investigate earlier, armed with my trusty steam cleaner to find a huge patch of black fungus lurking behind my bedside cabinet, a major cause of allergies in 31 per cent of us. No wonder I spend the night sneezing my head off and wake up breathing like someone making a dirty phone call.
But an even bigger culprit than mould is house dust mites, which cause 58 per cent of us to react badly.
And because the symptoms are strikingly similar to colds and flu, few of us don't recognise, and therefore don't treat, the cause of the problem.
The worse place for indoor allergy sufferers is the bedroom. Now before you read the next bit, get ready to be grossed out: the average bed is home to around two million house dust mites; and the average pillow DOUBLES in weight over a period of six months because of house dust mite faeces. Makes you want to sleep in a hammock, doesn't it?
Lindsey McManus, Deputy Chief Executive of Allergy UK explained: "Allergens that are found in the home become more of a problem at this time of the year as we start to turn up the central heating and close all the windows providing the ideal breeding ground for the house dust mite and encouraging mould spores to increase because of the lack of ventilation."
So what can you do about it to make your own and your children's lives less snuffly?
Well, sadly there's no cure for 'home fever' but there is lots you can do to manage the symptoms and reduce the amount of indoor allergens in the home.
Lindsey McManus offered these tips:
• Dust regularly but use a damp duster first, then a dry cloth. Otherwise, you are just moving the dust around.
• Wash bedding once a week at 60°C or higher to remove house dust mites. Allergy UK's research revealed 16 washing bedding at 30 or 40 degrees, house dust mites are set to stay.
• Regularly steam clean carpets and curtains.
• Use allergen-proof barrier covers on mattresses, duvets and pillows.
• Replace your mattress every 8-10 years. The research found 13 have kept theirs for 20 years.
• Buy new pillows every year - don't wait five years or more like the 25% of allergy sufferers out there.
• Use an air purifier to help remove and reduce allergens such as pollen, house dust mite debris and mould spores.
• Moulds flourish in damp environments, therefore one of the best ways to prevent their growth is VENTILATION.
• Thorough cleaning of the kitchen, bathroom and utility room with subsequent ventilation of these areas will help prevent mould growth.
• Open windows and close internal kitchen and bathroom doors when cooking, showering or bathing to prevent steam entering other rooms. Keep bathroom surfaces dry. Do not hang wet clothes inside or over radiators.
• Do not hang clothes in damp cupboards or pack clothes too tightly in wardrobes.
• If you do find mould, wash it off with diluted bleach, but you should also investigate why you have damp in the first place.
And finally, If you think you might be suffering from an indoor allergy, call Allergy UK's helpline on 01322 619898.