title: Prevalence of Circadian Misalignment and Its Association With Depressive Symptoms in Delayed Sleep Phase Disorder.
abstract: To examine the prevalence of circadian misalignment in clinically diagnosed delayed sleep phase disorder (DSPD) and to compare mood and daytime functioning in those with and without a circadian basis for the disorder.
  
  
  
  One hundred and eighty-two DSPD patients aged 16-64 years, engaged in regular employment or school, underwent sleep-wake monitoring in the home, followed by a sleep laboratory visit for assessment of salivary dim light melatonin onset (DLMO). Based on the DLMO assessments, patients were classified into two groups: circadian DSPD, defined as DLMO occurring at or after desired bedtime (DBT), or non-circadian DSPD, defined as DLMO occurring before DBT.
  
  
  
  One hundred and three patients (57%) were classified as circadian DSPD and 79 (43%) as non-circadian DSPD. DLMO occurred 1.66 hours later in circadian DSPD compared to non-circadian DSPD (p < .001). Moderate-severe depressive symptoms (Beck Depression Inventory-II) were more prevalent in circadian DSPD (14.0%) than in non-circadian DSPD (3.8%; p < .05). Relative to non-circadian DSPD patients, circadian DSPD patients had 4.31 times increased odds of at least mild depressive symptoms (95% CI 1.75 to 10.64; p < .01). No group differences were found for daytime sleepiness or function, but DSPD symptoms were rated by clinicians to be more severe in those with circadian DSPD.
  
  
  
  Almost half of patients clinically diagnosed with DSPD did not show misalignment between the circadian pacemaker and the DBT, suggesting that the reported difficulties initiating sleep at the DBT are unlikely to be explained by the (mis)timing of the circadian rhythm of sleep propensity. Circadian misalignment in DSPD is associated with increased depressive symptoms and DSPD symptom severity.
authors.affiliation: Monash Institute of Cognitive and Clinical Neurosciences, School of Psychological Sciences, Monash University, Clayton, Victoria, Australia.|Cooperative Research Centre for Alertness, Safety and Productivity, Clayton, Victoria, Australia.|NHMRC Centre for Sleep and Circadian Neurobiology, Sydney, New South Wales, Australia.
authors.forename: Jade M
authors.initials: JM
authors.lastname: Murray
authors.affiliation: Monash Institute of Cognitive and Clinical Neurosciences, School of Psychological Sciences, Monash University, Clayton, Victoria, Australia.|Cooperative Research Centre for Alertness, Safety and Productivity, Clayton, Victoria, Australia.|NHMRC Centre for Sleep and Circadian Neurobiology, Sydney, New South Wales, Australia.
authors.forename: Tracey L
authors.initials: TL
authors.lastname: Sletten
authors.affiliation: Monash Institute of Cognitive and Clinical Neurosciences, School of Psychological Sciences, Monash University, Clayton, Victoria, Australia.|Cooperative Research Centre for Alertness, Safety and Productivity, Clayton, Victoria, Australia.|NHMRC Centre for Sleep and Circadian Neurobiology, Sydney, New South Wales, Australia.
authors.forename: Michelle
authors.initials: M
authors.lastname: Magee
authors.affiliation: Cooperative Research Centre for Alertness, Safety and Productivity, Clayton, Victoria, Australia.|NHMRC Centre for Sleep and Circadian Neurobiology, Sydney, New South Wales, Australia.|Woolcock Institute of Medical Research and Sydney Local Health District, University of Sydney, Sydney, New South Wales, Australia.|Sydney Nursing School, University of Sydney, New South Wales, Australia.
authors.forename: Christopher
authors.initials: C
authors.lastname: Gordon
authors.affiliation: Cooperative Research Centre for Alertness, Safety and Productivity, Clayton, Victoria, Australia.|Adelaide Institute for Sleep Health, School of Medicine, Flinders University, Adelaide, South Australia.
authors.forename: Nicole
authors.initials: N
authors.lastname: Lovato
authors.affiliation: Cooperative Research Centre for Alertness, Safety and Productivity, Clayton, Victoria, Australia.|NHMRC Centre for Sleep and Circadian Neurobiology, Sydney, New South Wales, Australia.|Woolcock Institute of Medical Research and Sydney Local Health District, University of Sydney, Sydney, New South Wales, Australia.
authors.forename: Delwyn J
authors.initials: DJ
authors.lastname: Bartlett
authors.affiliation: Robinson Research Institute, School of Medicine, Discipline of Obstetrics and Gynaecology, University of Adelaide, Adelaide, South Australia, Australia.
authors.forename: David J
authors.initials: DJ
authors.lastname: Kennaway
authors.affiliation: Cooperative Research Centre for Alertness, Safety and Productivity, Clayton, Victoria, Australia.|Adelaide Institute for Sleep Health, School of Medicine, Flinders University, Adelaide, South Australia.
authors.forename: Leon C
authors.initials: LC
authors.lastname: Lack
authors.affiliation: Cooperative Research Centre for Alertness, Safety and Productivity, Clayton, Victoria, Australia.|NHMRC Centre for Sleep and Circadian Neurobiology, Sydney, New South Wales, Australia.|Woolcock Institute of Medical Research and Sydney Local Health District, University of Sydney, Sydney, New South Wales, Australia.
authors.forename: Ronald R
authors.initials: RR
authors.lastname: Grunstein
authors.affiliation: Monash Institute of Cognitive and Clinical Neurosciences, School of Psychological Sciences, Monash University, Clayton, Victoria, Australia.|Cooperative Research Centre for Alertness, Safety and Productivity, Clayton, Victoria, Australia.|NHMRC Centre for Sleep and Circadian Neurobiology, Sydney, New South Wales, Australia.|Division of Sleep and Circadian Disorders, Departments of Medicine and Neurology, Brigham and Women's Hospital; Division of Sleep Medicine, Harvard Medical School, Boston, MA; 9 Department of Medicine, Division of Sleep Medicine, Harvard Medical School, Boston, MA.
authors.forename: Steven W
authors.initials: SW
authors.lastname: Lockley
authors.affiliation: Monash Institute of Cognitive and Clinical Neurosciences, School of Psychological Sciences, Monash University, Clayton, Victoria, Australia.|Cooperative Research Centre for Alertness, Safety and Productivity, Clayton, Victoria, Australia.|NHMRC Centre for Sleep and Circadian Neurobiology, Sydney, New South Wales, Australia.|Division of Sleep and Circadian Disorders, Departments of Medicine and Neurology, Brigham and Women's Hospital; Division of Sleep Medicine, Harvard Medical School, Boston, MA; 9 Department of Medicine, Division of Sleep Medicine, Harvard Medical School, Boston, MA.
authors.forename: Shantha M W
authors.initials: SM
authors.lastname: Rajaratnam
mesh_terms: D000293:Adolescent; D000328:Adult; D000339:Affect; D002940:Circadian Rhythm / Q000528:radiation effects; D003863:Depression / Q000150:complications* / Q000503:physiopathology / Q000523:psychology*; D005260:Female; D006801:Humans; D008027:Light; D008297:Male; D008550:Melatonin / Q000378:metabolism; D008875:Middle Aged; D015995:Prevalence; D012890:Sleep / Q000502:physiology / Q000528:radiation effects; D020178:Sleep Disorders, Circadian Rhythm / Q000150:complications* / Q000503:physiopathology* / Q000523:psychology; D055815:Young Adult
chemical_list: D008550:Melatonin
keywords: circadian misalignment.; delayed sleep; depression