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Siobhan Scarlett, Hugh Nolan, Daniel Carey, Rose Anne Kenny, Matthew O’Connell, 184
Adverse Change in Sleep Duration is Associated with a Decline in Cognition at Two-Year Follow Up, Age and Ageing, Volume 47, Issue suppl_5, September 2018, Pages v13–v60, https://doi.org/10.1093/ageing/afy140.135Close - Share Icon Share
Background: Sleep difficulties become increasingly common as we age. This study assessed the relationship between changes in sleep duration and cognitive decline at two-year follow up in a sample of older adults in Ireland.
Methods: Data are from Wave 2 and Wave 3 (2 year interval) of The Irish Longitudinal Study on Ageing (TILDA), a nationally representative longitudinal study of adults ≥50 years. Cognition was assessed using the Mini Mental State Examination (MMSE). Sleep duration was self-reported. 5,994 participants aged 52 and over were included in the analysis sample. Sleep duration was categorised as short sleep (≤5 hours), optimal sleep (6–8 hours) and long sleep (≥9 hours). A mixed effects negative binomial model was used to assess longitudinal changes in MMSE error rate. The model controlled for potential confounders.
Results: 54% of the sample were female. Mean age at Wave 2 was 64.5 years (SD: 8.8, range: 52–93). At baseline, 12.0% reported short sleep and 8.5% reported long sleep. At follow-up, 8.2% of the sample reported a change from optimal to short sleep and 6.8% reported a change from optimal to long sleep. No significant differences in MMSE errors were found in those who did not transition between sleep duration categories, or those who transitioned to short sleep. Change from optimal to long sleep was associated with a greater increase in MMSE errors compared to those maintaining optimal duration (IRR [95% CI] = 1.19 [1.06–1.34], p < 0.01). Adjustment for covariates slightly reduced this effect (IRR [95% CI] = 1.17 [1.04–1.32], p < 0.01).
Conclusion: Increasing from optimal to long duration sleep over two years is associated with faster concurrent decline in cognitive function in older adults. No other pattern of sleep duration showed a significant association with cognitive decline at two-year follow up. This suggests that those reporting an increase in sleep duration may be experiencing accelerated cognitive decline.
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