Estimating the dim light melatonin onset of adolescents within a 6-h sampling window: the impact of sampling rate and threshold method.
Circadian rhythm sleep-wake disorders (CRSWDs) often manifest during the adolescent years. Measurement of circadian phase such as the dim light melatonin onset (DLMO) improves diagnosis and treatment of these disorders, but financial and time costs limit the use of DLMO phase assessments in clinic. The current analysis aims to inform a cost-effective and efficient protocol to measure the DLMO in older adolescents by reducing the number of samples and total sampling duration.



A total of 66 healthy adolescents (26 males) aged 14.8-17.8 years participated in a study; they were required to sleep on a fixed baseline schedule for a week before which they visited the laboratory for saliva collection in dim light (<20 lux). Two partial 6-h salivary melatonin profiles were derived for each participant. Both profiles began 5 h before bedtime and ended 1 h after bedtime, but one profile was derived from samples taken every 30 min (13 samples) and the other from samples taken every 60 min (seven samples). Three standard thresholds (first three melatonin values mean + 2 SDs, 3 pg/mL, and 4 pg/mL) were used to compute the DLMO. An agreement between DLMOs derived from 30-min and 60-min sampling rates was determined using Bland-Altman analysis; agreement between the sampling rate DLMOs was defined as ± 1 h.



Within a 6-h sampling window, 60-min sampling provided DLMO estimates within ± 1 h of DLMO from 30-min sampling, but only when an absolute threshold (3 or 4 pg/mL) was used to compute the DLMO. Future analyses should be extended to include adolescents with CRSWDs.
Biological Rhythms Research Laboratory, Department of Behavioral Sciences, Rush University Medical Center, 1645 W. Jackson Blvd, Chicago, IL 60612, USA. Electronic address: stephanie_j_crowley@rush.edu.
Stephanie J
SJ
Crowley
Biological Rhythms Research Laboratory, Department of Behavioral Sciences, Rush University Medical Center, 1645 W. Jackson Blvd, Chicago, IL 60612, USA.
Christina
C
Suh
Biological Rhythms Research Laboratory, Department of Behavioral Sciences, Rush University Medical Center, 1645 W. Jackson Blvd, Chicago, IL 60612, USA.
Thomas A
TA
Molina
Community Systems and Mental Health Nursing, Rush University Medical Center, 1653 W. Congress Parkway, Chicago, IL 60612, USA.
Louis F
LF
Fogg
Department of Medicine, Division of Pulmonary, Critical Care, and Sleep Medicine, University Medicine, Rhode Island Hospital, and Alpert Medical School of Brown University, 593 Eddy Street, Providence, RI, USA; Sleep for Science Research Laboratory, Department of Psychiatry & Human Behavior, Alpert Medical School of Brown University, 300 Duncan Drive, Providence, RI 02906, USA.
Katherine M
KM
Sharkey
Sleep for Science Research Laboratory, Department of Psychiatry & Human Behavior, Alpert Medical School of Brown University, 300 Duncan Drive, Providence, RI 02906, USA; Centre for Sleep Research, University of South Australia, GPO Box 2471, Adelaide, South Australia 5001, Australia.
Mary A
MA
Carskadon
D000293:Adolescent; D005260:Female; D006801:Humans; D008027:Light; D008297:Male; D008550:Melatonin / Q000032:analysis*; D012463:Saliva / Q000737:chemistry; D020178:Sleep Disorders, Circadian Rhythm; D013048:Specimen Handling / Q000379:methods*; D013997:Time Factors
D008550:Melatonin
Adolescent; Circadian; Circadian rhythm sleep–wake disorder; DLMO; Dim light melatonin onset; Sampling rate