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Updated: Aug 9, 2025
Human Circadian Phenotyping and Diurnal Performance Testing in the Real World
Published on: April 7, 2020
Creating the Cave: Conducting Circadian Science in Early Childhood
Lauren E Hartstein1, Sachi D Wong1, Leen Abbas1
1Department of Integrative Physiology, University of Colorado Boulder, Boulder, CO 80309, USA.
Insights
Measuring dim light melatonin onset (DLMO) in young children at home is feasible. This study offers strategies for accurate circadian timing assessments in preschoolers and toddlers.
Area of Science:
- Chronobiology
- Pediatric Sleep Medicine
- Circadian Physiology
Background:
- Assessing the body's internal clock timing (circadian system) typically involves physiological markers like saliva, serum, or temperature.
- In-laboratory dim light melatonin onset (DLMO) is standard for adults and adolescents, but challenging for young children (toddlers and preschoolers).
- Existing methods require adaptation for reliable DLMO measurement in preschool-aged children.
Purpose of the Study:
- To provide effective tools and strategies for conducting in-home dim light melatonin onset (DLMO) assessments in children aged 2-5 years.
- To establish a rigorous protocol for measuring circadian timing in young children within a familiar home environment.
- To address challenges associated with in-home studies, such as potential light exposure and data completeness.
Main Methods:
- Utilized a successful in-home protocol for DLMO assessments in approximately 250 children aged 2-5 years over 15 years.
- Collected actigraphy data alongside salivary melatonin samples.
- Developed strategies for training child participants and converting homes into dim-light environments ('caves').
Main Results:
- Demonstrated the feasibility of conducting in-home DLMO assessments in young children.
- Collected reliable circadian timing data from a significant cohort of preschoolers and toddlers.
- Identified strategies to enhance participant compliance and data quality in home-based studies.
Conclusions:
- In-home DLMO assessment is a viable and comfortable method for determining circadian timing in young children.
- The described protocol offers practical solutions for overcoming challenges in pediatric circadian research.
- Findings support the use of adapted in-home methods for accurate sleep and circadian rhythm assessments in early childhood.
Abstract:
In humans, physiological outputs of the body's internal clock (i.e., saliva, serum, and temperature) can be collected to quantify the timing of the circadian system. In-lab assessment of salivary melatonin in a dimly lit environment is a common approach for adolescents and adults; however, the reliable measurement of melatonin onset in toddlers and preschoolers requires a modification of laboratory methods. For > 15 years, we have successfully collected data from ~250 in-home dim light melatonin onset (DLMO) assessments of children aged 2-5 years. Although in-home studies of circadian physiology may introduce a host of challenges and may increase the risk of incomplete data (e.g., accidental light exposure), in-home studies afford more comfort (e.g., less arousal in children) and flexibility for families. Here, we provide effective tools and strategies to assess children's DLMO, a reliable marker of circadian timing, through a rigorous in-home protocol. We first describe our basic approach, including the study protocol, collection of actigraphy data, and strategies for training child participants to complete procedures. Next, we detail how to convert the home into a "cave", or dim-light environment, and present guidelines for timing the salivary data collection. Lastly, we provide helpful tips to increase participants' compliance based upon behavioral and developmental science tenets.
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