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Table 2 Frequencies of each sleep category at 6 and 12 months

From: Sleep during infancy, inhibitory control and working memory in toddlers: findings from the FinnBrain cohort study

  6 months 12 months P value*
Cut-offs 10th, 10-90th, 90th N (%) Cut-offs 10th, 10-90th, 90th N (%)
Nighttime sleep duration Short (≤8.50 h) 39 (12.4) Short (< 9 h) 42 (14.9) < 0.001
Intermediate (8.51-11 h) 196 (62.2) Medium (9.01–11) 142 (50.5) 0.098
Long (> 11 h) 80 (25.4) Long (> 11) 97 (34.5) < 0.001
Daytime sleep duration Short (≤2.25 h) 50 (15.8) Short (≤1.50 h) 29 (10.1) < 0.001
Intermediate (2.26–5.33 h) 233 (73.5) Medium (1.51–3.50 h) 211 (73.8) 0.428
Long (> 5.33 h) 34 (10.7) Long (> 3.50 h) 46 (16.1) 0.009
Total sleep duration per 24 h Short (≤12 h) 46 (14.6) Short (≤11 h) 34 (12.5) 0.006
Intermediate (12.01–15.30 h) 235 (74.6) Medium (11.01-14 h) 204 (73.1) 0.351
Long (> 15.30 h) 34 (10.8) Long (> 14 h) 40 (14.3) 0.010
% daytime sleep duration / total sleep Low (≤18.52%) 33 (10.5) Low (≤13%) 31 (11.1) 0.174
Intermediate (18.53–36%) 248 (78.7) Medium (13.01–27%) 224 (80.3) 0.202
High (> 36%) 34 (10.8) High (> 27.01%) 24 (8.6) 0.008
Frequency of night awakenings Low (≤0.5times) 33 (10.6) Low (≤0times) 31 (11.3) 0.165
Intermediate (0.6-4times) 245 (78.5) Medium (0.1–3.50times) 216 (78.5) < 0.001
High (>4times) 34 (10.9) High (> 3.50times) 28 (10.2) 0.004
Time awake at night Short (≤0 h) 51 (16.9) Short (≤0.01 h) 28 (11.0) < 0.001
Intermediate (0.01–0.75 h) 214 (71.1) Medium (0.02–0.83 h) 186 (73.2) 0.031
Long (> 0.75 h) 36 (12.0) Long (> 0.83 h) 40 (15.7) 0.027
  1. We created the cut-offs based on the 10th, 10-90th and 90th percentiles; these cut-offs follow the National Sleep Foundation’s sleep duration recommendations (Hirshkowitz et al., 2015)
  2. *Chi-square test was used to examine the difference in the proportions at 6 months compared to 12 months, for each of the sleep categories. Here only the p values are presented