Abstract
Several self-report scales have been developed to measure morningness, or the preference for early morning or late evening activity (i.e., larks vs. owls). This individual difference in human circadian (time-of-day) rhythms has applications in the selection and placement of shiftworkers for night work in industry.
Researchers have recently questioned the suitability of existing scales for people with alternate sleep-wake schedules and lifestyles. These factors may also render existing scales inappropriate for use in some cultures. To address this deficiency, we developed a new morningness scale (the preferences scale) that is not yoked to specific times of the 24-hour day and has a simplified response format.
Data on the preferences scale were collected from university students (total N=1,212) in four countries (U.S., England, Holland, and Spain). Responses on external validity measures (self-rated alertness over the waking day and actual and preferred arise and bed times) and another morningness scale (for comparative purposes) were also collected. Although scale statistics (aggregate and by country) suggest that the psychometric properties of the preferences scale were adequate, scale mean differences existed across countries. These results may indicate cultural, as well as the established biological, differences in morningness. However, a more thorough psychometric assessment is needed to substantiate this possibility.
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