I remember reading (I don't remember where) about Greek units in the early days of Viet Nam, that got buck naked for night ambushes/raids, the theory being that if they felt anything in clothes, they killed it (not to mention the psychological impact of having hairy, naked, Greeks invading). I don't know how true it was, but tactically, it makes sense, in an environment where touch takes over for sight (if your troops aren't hung up over the idea of fighting in the nude).