Department of Psychology, Polytechnic South West, Plymouth, UK.
The relationship between mood and peak flow (PEF) was examined in 10 adult asthmatics by taking twice daily readings over 15 days. Three subjects showed a clear overall mood-PEF relationship but this effect was attributable to recordings taken in the evening and not those taken in the morning. The size of the mood-PEF relationship correlated significantly with the percentage difference between morning and evening PEF. The results are discussed in terms of the direction of causality between mood and PEF and the need to examine individual differences in the mood-PEF relationship.