title: Individual differences in human circadian rhythms.
abstract: Research into individual differences in circadian rhythms is reviewed, particularly morningness-eveningness. It was hypothesised that extraverts would be inclined towards eveningness and introverts towards morningness. Forty-eight subjects took regularly their oral temperature. Peak times were identified from smoothed temperature curves. Results showed that extraverts had a peak time insignificantly later than introverts. Re-grouping of the data into the morningness-eveningness dimension, based upon the results of a self assessment questionnaire, showed that evening types had significantly later peak times than morning types. Morningness-eveningness was not significantly ocrrelated with extraversion-introversion, although there was a trend. No significant differences were found for sleep lengths with either groupings, or for sleep-wake habits within extraversion-introversion. Morning types retired and arose significantly earlier than evening types. Although sleep-wake habits and extraversion-introversion help to determine peak times there are other contributory factors to peak time which appear to be partly covered by the questionnaire.
mesh_terms: D000293:Adolescent; D000328:Adult; D001831:Body Temperature; D002940:Circadian Rhythm; D005120:Extraversion, Psychological; D005260:Female; D006801:Humans; D007206:Individuality; D007439:Introversion, Psychological; D008297:Male; D009055:Mouth; D012890:Sleep