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Higher sleep variability is associated with poorer memory trajectories over time in middle-aged and older adults

In the ALBION study of 184 adults (mean age 65, 65% women), time-varying analyses showed that sleep variability had robust non-linear associations with poorer memory trajectories over a 1.5-year follow-up, remaining significant after FDR correction. Cross-sectionally, more nightly awakenings were associated with poor memory and attention speed. The findings suggest that objective indicators of sleep continuity, particularly sleep variability, are most consistently related to domain-specific cognitive outcomes, with strongest evidence for memory decline over time.

Last updated: Aug 8, 2026•0 RCTs•📖 Read as article →

Evidence Score

Evidence Score34/100
Human RCT☆☆☆☆☆
Meta-analysis☆☆☆☆☆
Mechanism★★★★★
Safety★★★★☆
Confidencelow

Study Evidence

Study 1. Objective Sleep Measures and Cognition in Middle-Aged and Older Adults: A Cross-Sectional and Longitudinal Analysis in the ALBION Study.

observational

Tsapanou A, Margoni A, Pavlou E, Ntanasi E, Mamalaki E, Manolakos E, Yannakoulia M, Scarmeas N, Papandreou C · Medical sciences (Basel, Switzerland) (2026)

Participants: N/A
Duration: 1.5 years
Intervention: Objective sleep measures via 7-day wrist actigraphy (Actiwatch 2), including sleep duration, efficiency, variability, onset latency, wake after sleep onset, and number of awakenings
Outcome: Cognitive performance assessed by neuropsychological battery (memory, executive function, visuospatial ability, language, attention speed, global composite) at baseline and over 1.5-year follow-up
Effect Size: N/A (specific effect sizes not reported in abstract)
Population: Middle-aged and older adults (age > 40) from the ALBION study, including cognitively healthy individuals and those with mild cognitive impairment (N=184 at baseline, n=93 at follow-up)

Result:

PubMed: 42506309DOI: 10.3390/medsci14030340

Mechanism Graph

Sleep variability disrupts circadian rhythms and neural consolidation processes
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Irregular sleep patterns impair hippocampal-dependent memory consolidation during sleep
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Fragmented sleep reduces slow-wave sleep and synaptic homeostasis
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Result: Accelerated decline in memory performance over time

Limitations

  • ⚠Small sample size at follow-up (n=93) may limit generalizability and statistical power
  • ⚠Observational design cannot establish causality between sleep variability and cognitive decline
  • ⚠Short follow-up duration (1.5 years) may not capture long-term cognitive trajectories

Frequently Asked Questions

What is sleep variability and why is it important for cognition?▼

Sleep variability refers to day-to-day fluctuations in sleep duration and timing. The study found it was the most robust predictor of memory decline, suggesting that irregular sleep patterns may be more harmful than average sleep duration alone.

How was sleep measured in this study?▼

Sleep was measured objectively using wrist actigraphy (Actiwatch 2) over 7 days, capturing metrics like sleep duration, efficiency, variability, onset latency, wake after sleep onset, and number of awakenings.

Did the study find any cognitive benefits of better sleep?▼

Yes, higher baseline sleep efficiency was associated with better memory and language performance over follow-up, while longer wake after sleep onset, more awakenings, and longer sleep onset latency were linked to less favorable cognitive trajectories.

Who participated in the ALBION study?▼

Participants were middle-aged and older adults (mean age 65, 65% women) from Greece, including both cognitively healthy individuals and those with mild cognitive impairment.

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References

  1. 1.Tsapanou A, Margoni A, Pavlou E, Ntanasi E, Mamalaki E, Manolakos E, Yannakoulia M, Scarmeas N, Papandreou C. "Objective Sleep Measures and Cognition in Middle-Aged and Older Adults: A Cross-Sectional and Longitudinal Analysis in the ALBION Study.." Medical sciences (Basel, Switzerland), 2026. PMID: 42506309 DOI: 10.3390/medsci14030340
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