Falling asleep: the determinants of sleep latency
- G M Nixon1,
- J M D Thompson2,
- D Y Han2,
- D M O Becroft2,
- P M Clark2,
- E Robinson3,
- K E Waldie4,
- C J Wild5,
- P N Black6,
- E A Mitchell2
- 1Ritchie Centre for Baby Health Research, Monash Institute of Medical Research, Monash University, Melbourne, Australia
- 2Department of Paediatrics, University of Auckland, Auckland, New Zealand
- 3Section of Epidemiology and Biostatistics, School of Population Health, University of Auckland, Auckland, New Zealand
- 4Department of Psychology, University of Auckland, Auckland, New Zealand
- 5Department of Statistics, University of Auckland, Auckland, New Zealand
- 6Department of Pharmacology and Clinical Pharmacology, University of Auckland, Auckland, New Zealand
- Correspondence to Professor E A Mitchell, Department of Paediatrics, University of Auckland, Private Bag 92019, Auckland, New Zealand; e.mitchell{at}auckland.ac.nz
- Accepted 19 April 2009
- Published Online First 24 July 2009
Abstract
Background: Difficulty falling asleep (prolonged sleep latency) is a frequently reported problem in school-aged children.
Aims: This study aimed to describe the distribution of sleep latency and factors that influence its duration.
Methods: 871 children of European mothers were recruited at birth. 591 (67.9%) children took part in the follow-up at 7 years of age. Sleep and daytime activity were measured objectively by an actigraph worn for 24 h.
Results: Complete sleep data were available for 519 children (87.8%) with a mean age of 7.3 years (SD 0.2). Median sleep latency was 26 minutes (interquartile range 13–42). Higher mean daytime activity counts were associated with a decrease in sleep latency (−1.2 minutes per 102 movement count per minute, p = 0.05). Time spent in sedentary activity was associated with an increase in sleep latency (3.1 minutes per hour of sedentary activity, p = 0.01).
Conclusions: These findings emphasise the importance of physical activity for children, not only for fitness, cardiovascular health and weight control, but also for promoting good sleep.
Footnotes
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Funding The initial study was funded by the Health Research Council of New Zealand. The 12-month postal questionnaire was funded by Hawkes Bay Medical Research Foundation. The 3.5-year follow-up study was funded by Child Health Research Foundation, Becroft Foundation and Auckland Medical Research Foundation. The 7-year follow-up study was funded by Child Health Research Foundation. EAM and JMDT are supported by the Child Health Research Foundation. The 7-year follow-up study was conducted in the Children’s Research Centre, which is supported in part by the Starship Foundation and the Auckland District Health Board.
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Competing interests None.
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Ethics approval The study received approval from the Auckland Ethics Committee.
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Patient consent Obtained.








