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Title: Diurnal preference in older men and women : relationship with light, PER3 genotype and sleep wake timing
Author: Staples, Victoria Shana Lydia
ISNI:       0000 0004 2684 1414
Awarding Body: University of Surrey
Current Institution: University of Surrey
Date of Award: 2009
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This study explored the Horne Ostberg Morningness Eveningness Questionnaire (HO MEQ; Horne and Ostberg, 1976) as a useful tool in the measurement of diurnal preference in those over 60 years of age. The HO MEQ and Usual Sleep Patterns Questionnaire were completed by 376 respondents over 60, with 127 providing samples for PER3 VNTR genotyping. HO MEQ score continued to increase with increasing age, but at a lesser rate, in the over 60 age group compared with those aged 18-59 years. This data was combined with data from Jones et al. (2007) and Robilliard et al. (2002) to enable comparison of factor structure across age using multiple group confirmatory factor analysis. The model derived in the 18-29 age group was of acceptable fit in all age groups except those over 60 years. The HO MEQ measured similar substantive factors across all age groups, but factors identified in the over 60 age group used different indicator questions, the correlation between ‘morning’ and ‘evening’ factors declined with increasing age, and the ‘morning’ factor accounted for more variance compared with younger age groups. The association of the PER3 VNTR polymorphism and HO-MEQ score continued in the over 60 age group, but the frequency of the 4-repeat allele was lower than in younger age groups. The 4-repeat allele frequency was significantly different between morning types (M-types) and evening-types (E-types) in the 50+ age group, but investigation of further age group breakdowns requires a larger sample in the 50-59 age group. 12 M-types and 11 E-types over 60 years of age were identified by liner regression of HO MEQ score and age and completed a 14-day light actigraphy/diary study. The HO MEQ successfully distinguished between early and late sleep schedules. Older E-types received greater exposure to bright light than older M-types. Significant differences in the timing of light exposure profiles between M-types and E-types were a product of differences in sleep-wake timing as previously observed in younger populations. This study has shown that the HO MEQ is a useful measure of diurnal preference in those over 60, but this underlying concept may be measured differently in this age group. The observed changes in factor structure and early morning light exposure may contribute to the observed increase in morningness with age.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral