HormonesMelatonin

Morning melatonin profiles are highly variable in preschool-aged children, limiting the reliable calculation of dim-light melatonin offset (DLMOff).

In a study of 20 healthy preschoolers (mean age 4.31 years, 45% female), evening melatonin profiles consistently allowed calculation of DLMO in all participants, but morning melatonin levels were highly variable, enabling DLMOff calculation in only 8 participants. Among those 8, later DLMOff was strongly associated with later chronotype (r=0.81), sleep offset (r=0.84), and midsleep (r=0.80).

Last updated: Aug 6, 2026•0 RCTs•📖 Read as article →

Evidence Score

Evidence Score34/100
Human RCT☆☆☆☆☆
Meta-analysis☆☆☆☆☆
Mechanism★★★★★
Safety★★★★☆
Confidencelow

Study Evidence

Study 1. Variable Morning Melatonin Profiles Limit Determination of Dim-Light Melatonin Offset in Preschool-Aged Children.

observational

Hartstein LE, Stowe SR, Wright KP, Diniz Behn C, LeBourgeois MK · Journal of biological rhythms (2026)

Participants: N/A
Duration: 7 days of consistent sleep schedule plus one assessment day
Intervention: Consistent sleep schedule for 7 days followed by in-home circadian assessment with morning and evening saliva sampling.
Outcome: Dim-light melatonin offset (DLMOff) and dim-light melatonin onset (DLMO) calculated using a 4 pg/ml threshold; actigraphic sleep timing (bedtime, sleep onset, midsleep, sleep offset).
Effect Size: r=0.81 for DLMOff and chronotype; r=0.84 for DLMOff and sleep offset; r=0.80 for DLMOff and midsleep
Population: Healthy preschool-aged children (mean age 4.31 ± 0.34 years, 45% female).

Result:

PubMed: 42504584DOI: 10.1177/07487304261469609

Mechanism Graph

Children maintained a consistent sleep schedule for 7 days
↓
Saliva samples collected in 20-30 min intervals in the morning and evening
↓
Melatonin levels measured and compared to a 4 pg/ml threshold
↓
Morning melatonin profiles were highly variable, limiting DLMOff calculation to only 40% of participants

Limitations

  • ⚠Small sample size (n=20) limits generalizability
  • ⚠DLMOff could only be calculated in 8 participants, reducing statistical power for morning phase analysis

Frequently Asked Questions

What is dim-light melatonin offset (DLMOff)?▼

DLMOff is the time in the morning when melatonin levels drop below a threshold (here 4 pg/ml), marking the end of the melatonin production period and serving as a marker of circadian phase.

Why was DLMOff difficult to measure in preschool children?▼

Morning melatonin levels were highly variable and often irregular, with 45% of children still having melatonin levels ≥4 pg/ml at habitual wake time, making it hard to determine a clear offset point.

How does DLMOff relate to sleep timing in children?▼

In the small subsample where DLMOff could be calculated, later DLMOff was strongly correlated with later chronotype (r=0.81), later sleep offset (r=0.84), and later midsleep (r=0.80).

What was the study design and duration?▼

This was an observational study where 20 healthy preschoolers maintained a consistent sleep schedule for 7 days, followed by a single in-home circadian assessment with saliva sampling.

Products

Affiliate links coming soon. We only recommend products that match the doses and forms used in the cited research.

References

  1. 1.Hartstein LE, Stowe SR, Wright KP, Diniz Behn C, LeBourgeois MK. "Variable Morning Melatonin Profiles Limit Determination of Dim-Light Melatonin Offset in Preschool-Aged Children.." Journal of biological rhythms, 2026. PMID: 42504584 DOI: 10.1177/07487304261469609
Disclaimer: This content is for educational purposes only and is not medical advice. Evidence scores reflect the quality and quantity of available research, not clinical recommendations. Always consult a healthcare professional before starting any supplement or intervention.