Although I insist that the research fails to reveal significant psychological damage from long-term imprisonment, this doesn't mean that we don't develop our little quirks.
Whilst we are often allowed to buy a duvet, I stick to prison sheets. Only sheets have an edge that is sharp, and as I fall asleep I run this edge between my toes. It keeps me happy...
Famously, I eschew drinking from cups or mugs. As I drink around three litres of tea or coffee a day, drinking out of a mug would see me forever hopping up and down to make more. Instead, I use a plastic one-litre water jug. As these are no longer issued to us, I guard my two and take them with me on transfers. Why two? One is for everyday use, and is never scrubbed clean. On the same theory that holds that teapots shouldn't have the tannin scrubbed out lest it affects flavour, so my jug long ago ceased to be transparent. It is brown-black, and looks disgusting. The other jug is a clean one, saved for use should royalty ever pop in for tea.
And I cannot sleep in silence. The TV or radio must be on in the background, preferably News 24 or the World Service, in order for me to get a decent night’s sleep.
As quirks go, these aren't too bad after thirty years, don't you think?