To get a decent sleep I nearly always use foam ear plugs when I travel, as I wake up to easily from any noise. I have a preferred brand and they work pretty well. You roll them between your fingers to press them into a stiff narrow cone shape that you can insert into your ear where they expand again. I have noticed recently that when I am in a hot and humid climate, I can roll however long I like I can't get them 'stiff' and can't get them deep into the ear. When I use the same plugs in a cooler less humid climate, they work fine again.

What can I do here? I keep them in a sealed plastic bag but that doesn't help. I though about putting them into a fridge for a while, but most places I am staying don't have one.