title: Nocturnal Melatonin Profiles in Patients with Delayed Sleep-Wake Phase Disorder and Control Sleepers.
abstract: A significant delay in the timing of endogenous circadian rhythms has been associated with delayed sleep phase disorder (DSPD). More recently, other mechanisms have also been proposed to account for this disorder. To further explore the etiology of DSPD, the present study compared nocturnal melatonin profiles of 26 DSPD patients (18 males, 8 females; age, 21.73 ± 4.98 years) and 17 normally timed good sleepers (10 males, 7 females; age, 23.82 ± 5.23 years) in a time-free, dim-light (<10 lux) laboratory environment. A 30-h modified constant routine with alternating 20-min sleep opportunities and 40 min of enforced wakefulness was used to measure the endogenous melatonin circadian rhythm. Salivary melatonin was sampled half-hourly from 1820 h to 0020 h and then hourly from 0120 h to 1620 h. DSPD patients had significantly later timed melatonin profiles that were delayed by approximately 3 h compared to normal sleepers, and there were no notable differences in the relative duration of secretion between groups. However, melatonin secretion between dim-light melatonin onset (DLMO) and acrophase was less prominent in DSPD patients compared to good sleepers, who showed a more acute initial surge of melatonin following the DLMO. Although the regulatory role of melatonin is unknown, abnormal melatonin profiles have been linked to psychiatric and neurological disorders (e.g., major depression, obsessive compulsive disorder, Parkinson disease). These results therefore suggest that in addition to a delayed endogenous circadian rhythm, a diminished initial surge of melatonin secretion following DLMO may contribute to the etiology of DSPD.
authors.affiliation: Flinders University of South Australia, Adelaide, South Australia, Australia gorica.micic@flinders.edu.au.
authors.forename: Gorica
authors.initials: G
authors.lastname: Micic
authors.affiliation: Flinders University of South Australia, Adelaide, South Australia, Australia.
authors.forename: Nicole
authors.initials: N
authors.lastname: Lovato
authors.affiliation: Flinders University of South Australia, Adelaide, South Australia, Australia.
authors.forename: Michael
authors.initials: M
authors.lastname: Gradisar
authors.affiliation: Rush University Medical Center, Chicago, Illinois, USA.
authors.forename: Helen J
authors.initials: HJ
authors.lastname: Burgess
authors.affiliation: Appleton Institute, Central Queensland University, Adelaide, South Australia, Australia.
authors.forename: Sally A
authors.initials: SA
authors.lastname: Ferguson
authors.affiliation: Robinson Research Institute, School of Paediatrics and Reproductive Health, University of Adelaide, Adelaide, South Australia, Australia.
authors.forename: David J
authors.initials: DJ
authors.lastname: Kennaway
authors.affiliation: Flinders University of South Australia, Adelaide, South Australia, Australia.
authors.forename: Leon
authors.initials: L
authors.lastname: Lack
mesh_terms: D056044:Actigraphy / Q000379:methods / Q000706:statistics & numerical data; D000293:Adolescent; D000328:Adult; D000704:Analysis of Variance; D002940:Circadian Rhythm / Q000502:physiology*; D005260:Female; D006801:Humans; D007118:Immunoassay; D008297:Male; D008550:Melatonin / Q000378:metabolism*; D011446:Prospective Studies; D012463:Saliva / Q000737:chemistry; D012890:Sleep / Q000502:physiology*; D020178:Sleep Disorders, Circadian Rhythm / Q000378:metabolism* / Q000503:physiopathology*; D011795:Surveys and Questionnaires; D013997:Time Factors; D014851:Wakefulness / Q000502:physiology; D055815:Young Adult
chemical_list: D008550:Melatonin
keywords: bright-light therapy; circadian rhythm; dim-light melatonin onset; melatonin profiles; phase response curve; sleep disorder