Personality differences in the phase of circadian rhythms: a comparison of morningness and extraversion.
Vidacek-S; Kaliterna-L; Radosevic-Vidacek-B; Folkard-S
Ergonomics 1988 Jun; 31(6):873-888
A study of the influence of personality traits on circadian rhythm phases was conducted. Twenty eight undergraduate psychology students, 20 females, mean age 22.1 years, who had shown relatively low or high scores for extraversion and morningness on personality tests were studied. A battery of tests that measured vigilance and psychomotor performance was administered at 4 hour intervals over a 24 hour period. Subjects rated their subjective alertness using a visual analogue scale before and after each session. Skin conductance and heart rates were monitored during each test. Oral temperature was recorded before and after each session. A significant interaction was seen between time of day and morningness only for alertness and temperature. Morning types tended to have a higher amplitude in alertness rhythm than evening types. A statistically significant interaction between time of day and extraversion occurred only for alertness. Alertness peaked earlier in the day in the extraverts than in the introverts. A significant interaction occurred between time of day, extraversion, and morningness for performance on simple and choice reaction time tests in the battery. The authors conclude that their results support the notion that morningness is more important than extraversion in determining individual differences in circadian rhythm phases.
Laboratory-testing; Humans; Personality-traits; Psychophysiology; Circadian-rhythms; Task-performance; Physiological-measurements