This study used the biological model of experimental hypoglycaemia to examine the effect of a manipulation in mood-state on appraisal. Controlled hypoglycaemia was achieved using the hyperinsulinaemic glucose clamp technique. Mood, appraisal, and personality traits were assessed using well validated questionnaires. Our findings 1) reaffirm the existence of multiple arousal systems in the generation of moods, 2) show that the induction of a negative mood state does lead to more negative appraisals of a life situation, and 3) show that personality traits remain stable during the experience of negative emotions and cognitions. We conclude that hypoglycaemia, by inducing a state of tense tiredness in some individuals, may lead to more negative appraisals of a life situation but does not alter people's reporting of behavioural dispositions.