Characterizing sleep spindles in 11,630 individuals from the National Sleep Research Resource.

In contrast, both adult studies showed highly significant (all P <10 −15 , matched-pair t -tests) reductions in spindle density (12% and 15% reductions in SHHS and MrOS, N =2,597 and 958, respectively), amplitude (5 and 12%) and duration (2 and 2%) across the ∼5-year period, consistent with the cross-sectional analyses.

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We observed nominally significant interaction effects in both studies, consistent with relatively less decline in females (72% and 90% of the decline in males for CFS and SHHS, N =719 and 5,572, respectively, both P <0.05 from a linear regression on spindle density, controlling for standard covariates).

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