In a former life I used to be a product manager for a range of chilled foods. Every office at the company had its own fridge for storing product samples. It was absolutely ingrained in us that you pop a chilled product back in the fridge immediately after use. And like those forensic scientists who can age a corpse on the basis of its degree of maggot infestation, I could take one look at the bowing foil lid of a non-refrigerated yoghurt pot and know the precise moment when it would blow, projecting its creamy ectoplasm in random directions.
Fast forward 25 years and I am still very conscious about the ravages of unchilled storage as it applies to perishable foods - and latterly also perfumes. From my research on Basenotes I have learnt that the Osmotheque perfume museum in Versailles curates its ordinary scents at 10 degrees C and its citrus-dominant ones at 4 degrees C. I also gathered that glass atomizers preserve a scent better than plastic. But please don't ask if a glass atomizer at ambient temperature keeps a perfume longer than a refrigerated plastic one - my research didn't grapple with such fiendish interlocking variables...
But on the premise that cold was better than hot, during the brief heatwave that struck the UK at the end of June I bought a second hand beer chiller on Ebay for £50. It is set to 10 degrees and the citrus fragrances will jolly well have to take their chances, for I am darned if I am going to buy a separate chiller for them. The chiller contains most of my 50 full bottles, a box of plastic atomizers, and bags and bags of minis and samples. I still have two drawers' worth of overflow FBs, glass atomizers and more samples, so in retrospect I could easily have filled a fridge twice the size. Things have got to the stage where when you open the door, a bottle that you are not reaching for teeters to the edge of a shelf and falls off, like one of those rare snack vending machines that actually "vend".
I find the intermittent whirr of the fridge (in a cold spare bedroom) quite comforting, though the recent appearance of icy stalagmites just above the top shelf is a little concerning. For as well as heat and light, perfumes don't much care for humidity of course, but you can't have everything. It might not be a bad idea to defrost it, come to think of it.
So, not a perfect solution, but it's got to be a cut above the bathroom cabinet. : - )