Background: The aim of the present study was to investigate within-person life satisfaction (LS) dynamics for two age groups, 20-29 and 30-39 years, from 1984 to 1986 and to follow them over a 20-year period. Methods: Data from 1984 to 2008 were extracted from the large, prospective, longitudinal North-Trøndelag Health Study (HUNT), Norway. This paper includes data from more than 14,500 persons. Data were analysed using logistic regression, and LS dynamics were modelled using gender, time and self-rated health. Results: The analyses revealed that about 20% of people in these age groups had a stable level in LS, also known as set point. Long-term LS change, defined as ⩾2 SDs, was reported for 9% and 6% of people in the youngest and oldest age groups, respectively. A large proportion of more than 70% of people had fluctuations in their LS over a 20-year period. A significant decrease in within-person LS was seen for the age groups from 1984-86 to 1995-97 where a significant increase appeared from 1995-97 to 2006-08. For the initial 20-29 age group, the odds of having a higher score increased by 34%, and for the initial 30-39 age group, the within-person LS increase was 81%. Self-rated health was the most crucial variable influencing within-person LS. Conclusions: These findings suggest that a significant proportion of the responders had a long-term within-person LS change over the 20-year period.
Keywords: Within-person life satisfaction; age groups; cohorts; life satisfaction dynamics; set point; well-being.