Table 4.
Infant sleep–wake patterns by annual household income, adjusted for sex, birth weight for gestational age, and age at assessment
| Sleep–wake patterns | <$80k (N = 110) | $80–199k (N = 104) | >$200k (N = 84) | F (df) | P |
|---|---|---|---|---|---|
| 1 month | |||||
| Night sleep duration (minutes) | 460.0 (446.2, 473.9) | 465.0 (450.8, 479.3) | 457.4 (441.6, 473.2) | 0.26 (2, 300) | 0.77 |
| Longest continuous night sleep (minutes) | 283.4 (264.1, 302.7) | 291.6 (271.7, 311.5) | 267.5 (245.5, 289.5) | 1.30 (2, 300) | 0.27 |
| WASO (minutes) | 48.6 (42.9, 54.4) | 56.4 (50.5, 62.3) | 57.4 (50.9, 64.0) | 2.53 (2, 300) | 0.08 |
| Night wake bouts (episodes) | 3.4 (3.1, 3.7) | 3.2 (2.9, 3.6) | 3.3 (2.9, 3.7) | 0.15 (2, 300) | 0.83 |
| Daytime sleep duration (minutes) | 239.8 (228.8, 250.7) | 209.9 (198.7, 221.2) | 193.0 (180.6, 205.5) | 16.28 (2, 300) | <0.001 |
| Total sleep duration (minutes) | 708.4 (687.2, 729.6) | 684.5 (662.7, 706.3) | 657.5 (633.3, 681.7) | 4.86 (2, 300) | 0.008 |
| 6 months | |||||
| Night sleep duration (minutes) | 499.9 (488.1, 511.7) | 539.4 (527.2, 551.6) | 548.4 (534.8, 561.9) | 17.05 (2, 300) | <0.001 |
| Longest continuous night sleep (minutes) | 424.8 (406.8, 442.8) | 472.2 (453.6, 490.8) | 491.9 (471.3, 512.5) | 12.87 (2, 300) | <0.001 |
| WASO (minutes) | 56.4 (52.2, 60.5) | 57.5 (53.2, 61.8) | 62.5 (57.7, 67.2) | 1.98 (2, 300) | 0.14 |
| Night wake bouts (episodes) | 1.4 (1.2, 1.6) | 1.1 (0.9, 1.4) | 0.9 (0.6, 1.1) | 4.60 (2, 300) | 0.01 |
| Daytime sleep duration (minutes) | 154.4 (146.8, 162.0) | 134.8 (126.9, 142.7) | 135.5 (126.8, 144.3) | 7.79 (2, 300) | <0.001 |
| Total sleep duration (minutes) | 662.3 (650.4, 674.2) | 678.0 (665.8, 690.2) | 687.3 (673.8, 700.8) | 3.94 (2, 300) | 0.02 |
| Change between 1 month and 6 months* | |||||
| Night sleep duration (minutes) | 39.5 (22.8, 56.3) | 74.9 (57.6, 92.1) | 90.8 (71.7, 109.9) | 8.60 (2, 299) | <0.001 |
| Longest continuous night sleep (minutes) | 141.0 (116.8, 165.1) | 181.5 (156.5, 206.4) | 223.9 (196.4, 251.5) | 9.96 (2, 299) | <0.001 |
| WASO (minutes) | 7.7 (1.0, 14.3) | 1.2 (−5.7, 8.1) | 5.1 (−2.5, 12.7) | 0.88 (2, 299) | 0.42 |
| Night wake bouts (episodes) | −2.0 (−2.3, −1.6) | −2.1 (−2.5, −1.8) | −2.5 (−2.8, −2.1) | 1.90 (2, 299) | 0.15 |
| Daytime sleep duration (minutes) | −85.5 (−96.9, −74.1) | −75.1 (−86.9, −63.4) | −57.3 (−70.3, −44.3) | 5.21 (2, 299) | 0.006 |
| Total sleep duration (minutes) | −47.4 (−69.3, −25.6) | −5.6 (−28.0, 16.9) | 29.8 (5.0, 54.6) | 10.74 (2, 299) | <0.001 |
df = degrees of freedom. Sleep patterns in different household income groups are described using mean and 95% confidence interval adjusted for sex, birth weight for gestational age z-score, and age at assessment.
*Positive value means increased sleep duration from 1 month to 6 months; negative means decreased.