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Abstract
The purposes of this study were to analyze time-of-day and morningness-eveningness on the ability of working nurses to learn and recall at widely varying times of day, and to examine selected characteristics of the sample based on the morningness-eveningness trait.
Forty-one morning subjects and 40 evening subjects learned about two unfamiliar health topics, using a videotape or an article. Immediate and delayed recall was measured using multiple-choice tests and free or cued recall. Learning and recall sessions were scheduled at the subjects' "preferred" time or "off" time. Additionally subjects completed a Daily Habits and Lifestyle questionnaire and the Quick Word Test for use as a covariate.
Thirty-eight percent of the population sampled tended toward morningness, 18% tended toward eveningness. This skew toward morningness appeared to become more definite as subjects aged. Morning and evening subjects differed significantly for preferred study times. Morning subjects overwhelmingly preferred 8 AM to 10 AM, while evening subjects were spread over a period from 10 AM to midnight.
Three-way ANCOVA showed immediate and delayed recall performance was not significantly different when learning or recall occurred during the subject's "preferred" rather than "off" time. There was a trend toward better delayed recall scores if subjects learned at preferred times. Two-way ANCOVA revealed delayed recall for prose was better in morning subjects in the evening, p = .038, and total delayed recall performance was better in evening subjects if time of recall was the same as time of learning, p = .032.
Arousal, at time of learning, accounted for significant variance in video and prose recall scores. Morning and evening subjects differed significantly on subjective ratings of arousal at different times of day. Correlations between learning and recall scores for video and prose indicated a greater deterioration of memory for prose learning.
The study suggests that individual diurnal preferences, as a source of arousal, may influence delayed recall for certain tasks.
