I do think that I lose some confidence after losing two or three games in a row. I should take a break for awhile or a day but the desire to get back to even can often be overpowering. And that can lead to more losses.
Loosing streak

You are right, to take a break is probably the best thing to do, especially if you see you are playing below your actually level.

Eating, sleeping, emotion, and attitude can affect your play... even if you feel fine, try to think if you've had enough sleep, if you don't feel motivated to calculate, if something is upsetting you, etc. Losing your last game can be the thing that's upsetting you.

I like to listen to music I really enjoy while I play. It helps keep the motivation and mood the same... but sometimes I can feel myself slipping. I start miscalculating or I feel tried. Usually that's a good time to quit playing... sometimes I wait until I lose 1 or 2 games due to mistakes I don't usually make, and then I'll quit.
Do you noted also that sometimes you play just like a beginner, loosing against everybody? I guess this is a kind of "loosing effect", probably due to lack of confidence after loosing one or two games. I still have to analyse my games in this loosing streak, but I would like to hear your own experience in this subject. I do not know if this has something to do with playing in a computer instead with the iPad (which I usually use).