Introduction Previous research has indicated that poor subjective sleep quality is associated with lower fluid intelligence scores (Smith et al., 2019). However, it is not known whether subjective sleep continuity is associated with fluid intelligence, or with set-shifting or mental rotation accuracy, since these are closely related to fluid intelligence (Kafadar et al., 2016; Varriale et al., 2018). The aim of the study was to investigate the relationship between sleep continuity, assessed using daily subjective sleep diaries and fluid intelligence. It was hypothesised that sleep continuity would be positively associated with 1) fluid intelligence, 2) mental rotation and 3) set-shifting.

Methods A total of 39 healthy good sleepers completed a daily subjective sleep diary (Consensus Sleep Diary-M) for seven consecutive days electronically. On Day 7, participants completed three cognitive tasks (Ravens Standard Progressive Matrices, Wisconsin Card Sorting task and a Mental Rotation task). Standard measures of sleep continuity were derived from sleep diaries, including sleep onset latency (SOL), number of awakenings (NWAK), wake after sleep onset (WASO), time in bed (TIB) and sleep efficiency (SE%). Three Pearson’s correlations were conducted between the cognitive tasks and sleep continuity measures. All p-values were adjusted for multiple comparisons (adjusted p-value = .01).

Results Overall, no association was found between subjective sleep continuity (SOL, NWAK, WASO, TIB and SE%) and Ravens Standard Progressive Matrices, Wisconsin Card Sorting task, or Mental Rotation accuracy scores (all p-values > .01).

Discussion These results indicate that fluid intelligence, mental rotation and set-shifting are not associated with subjective sleep continuity. Previous literature has found associations between objective sleep measures and sleep spindle activity (Bódizs et al., 2014; Ujma et al., 2015), therefore fluid intelligence may only be associated with objective sleep architecture.