Faculty Profile

Circadian Group, Division of Sleep Medicine, Brigham and Women's Hospital
Chronobiology Core, Division of Sleep Medicine, Brigham and Women's Hospital

My research interests include both basic and applied aspects of circadian physiology. My recent work has focused on understanding individual differences in human circadian rhythms, including how aging affects circadian rhythms and how diurnal preference (morningness-eveningness) is related to individual differences in human circadian rhythms.
My research on aging examines several aspects of human circadian rhythmicity, including whether there are age-related changes in the response of the human circadian system to light; whether there are age-related differences in light exposure patterns in humans; how manipulation of the relationship between sleep and circadian rhythmicity affects sleep quality and quantity; whether pre-sleep melatonin administration can improve sleep quality in older people; and whether healthy older adults are more resistant to sleep deprivation than young adults.

The other major research area I am currently pursuing is studying individuals who are extreme early birds or night owls. My research on diurnal type is focused on how an individual's circadian period influences the timing of their daily biological rhythms, how the phase relationship between sleep and the timing of daily rhythms is related to an individual's morningness-eveningness preference, the magnitude of the circadian influence on sleep and performance in extreme diurnal types, and what role "clock genes" play in determining circadian period and diurnal type.

In addition to those areas described above, my research interests include understanding the underlying factors contributing to circadian rhythm sleep disorders such as shift-work dyssomnia, advanced and delayed sleep phase syndromes and jet lag, and pursuing novel treatments for those disorders.

Undergraduates:
Jason Rodriguez, 2001
Marie Cadet, 2001
Alison M. Laffan, 2001-2002
Alex S.W. Lowe, 2003-2004
Hannah Willson, 2005-2007
John Hares, 2005-2006
Stephanie Romiszewsk, 2005-2007
Fanuel Muindi, 2007-present
Rachel Zhang, 2007-present

Medical Students:
Rashad J. Harris, 2005
Van T. Nguyen, 2005

Post-doctoral Fellows:
Nayantara Santhi, PhD, 2002-2005
Anne-Marie Chang, PhD, 2003-present
Karine D. Scheuermaier, MD, 2006-present
Sean W. Cain, PhD, 2006-present
Mirjam Y. Münch, PhD, 2006-present 

NIH/NIA
Disrupted sleep in the elderly: circadian etiology
PI: Jeanne F. Duffy, MBA, PhD.
The goal of this project is to test a light treatment regimen that uses a blue-enriched fluorescent light source to better align the timing of the sleep-wake cycle and the phase of the circadian timing system in older individuals with complaints of sleep maintenance insomnia and/or early morning awakening.

NIH/NCCAM
Effect of vitamin B12 on the human circadian pacemaker
PI: Jeanne F. Duffy, MBA, PhD.
The goal of this project is to test vitamin B12's effects on circadian period in a placebo-controlled study in healthy subjects, using the forced desynchrony protocol to measure circadian period precisely.

NIH/NHLBI
Circadian & Genetic Evaluation of Extreme Sleep Timing
PI: Jeanne F. Duffy, MBA, PhD.
The goal of this project is to conduct a phenotypic and genetic evaluation of extreme diurnal types in order to determine the underlying chronobiologic and genetic basis of human diurnal preference. We will measure sleep timing, circadian phase, circadian period, and the circadian rhythm of sleep propensity, as well as assess known polymorphisms in circadian genes and explore novel polymorphisms, thereby linking specific genes with observable behavior.

NIH/NIA Program Project
Sleep Aging and Circadian Rhythm Disorders
PI:  Charles A. Czeisler, PhD. 
The goals of the Program Project are to understand how older people respond to chronic sleep restriction. The program will investigate changes in sleep, waking neurobehavioral performance, and metabolism, at the behavioral and electrophysical levels as well as at the neuro-anatomical level.
Role:  Co-Investigator, Project 1 Circadian and Homeostatic Sleep Regulation in Older People; Project Leader, Project 2 Alertness and Cognitive Performance in Sleep-Restricted Older People.

NIH/NIMH
Treatment of Circadian Sleep Disorders With Bright Light
PI:  Charles A. Czeisler, PhD, MD.
The goal of this project is to test the human circadian response to short-wavelength monochromatic light, including the phase-dependent resetting response, the melatonin-suppressing response, and the acute alerting response.
Role:  Co-Investigator.

NIH/NHLBI
Training in sleep, circadian and respiratory neurobiology
PI: Charles A. Czeisler, PhD.
The goal of this institutional training program is to provide a structured, comprehensive program to train outstanding individuals for academic positions in the broad field of sleep disorders medicine with specific expertise in basic science, patient-oriented or applied research.
Role: faculty preceptor.

HMS Program for Research and Investigation in Science and Math, Lecturer
HMS Explorations for Middle School Students Program, Laboratory Host
HMS Division of Sleep Medicine Institutional NRSA "Sleep, Aging and Circadian Rhythm Disorders", Preceptor
HMS Division on Aging Geriatric Psychiatry Summer Seminars, Lecturer
NSF Chautauqua Short Course for College Teachers, Faculty Member

Duffy JF, Zeitzer JM, Czeisler CA. Decreased sensitivity to phase-delaying effects of moderate intensity light in older subjects.
Neurobiol Aging. 2007 May;28(5):799-807. Epub 2006 Apr 18. [PMID: 16621166]

Duffy JF. Increased sleep disruption, reduced sleepiness in older subjects? Commentary on Circadian patterns of sleep, sleepiness, and performance in older and younger adults.
Sleep. 2005 Nov 1;28(11):1358-9. [PMID: 16335324]

Santhi N, Duffy JF, Czeisler CA. Scheduling of sleep/darkness affects the circadian phase of night shift workers.
Neuroscience Letters. 2005 Aug 26;384(3):316-20. [PMID: 15919151]

Duffy JF, Wright KP Jr. Entrainment of human circadian rhythms by light.
Journal of Biological Rhythms. 2005 Aug;20(4):326-38. [PMID: 16077152]

Duffy JF. Shift work and aging: Roles of sleep and circadian rhythms.
Clinics in Occupational and Environmental Medicine. 2003; 3:311-332.

Duffy JF, Dijk DJ. Getting through to circadian oscillators: Why use constant routines?
Journal of Biological Rhythms. 2002 Feb;17(1):4-13. [PMID: 11837947]

Duffy JF, Zeitzer JM, Rimmer DW, Klerman EB, Dijk DJ, Czeisler CA. Peak of circadian melatonin rhythm occurs later within the sleep of older subjects.
Am J Physiol Endocrinol Metab. 2002 Feb;282(2):E297-303. [PMID: 11788360]

Duffy JF, Czeisler CA. Age-related change in the relationship between circadian period, circadian phase, and diurnal preference in humans.
Neurosci Lett. 2002 Feb 1;318(3):117-20. [PMID: 11803113]

Duffy JF, Rimmer DW, Czeisler CA. Association of intrinsic circadian period with morningness-eveningness, usual wake time, and circadian phase.
Behav Neurosci. 2001 Aug;115(4):895-9. [PMID: 11508728]

Dijk DJ, Duffy JF, Czeisler CA. Age-related increase in awakenings: impaired consolidation of nonREM sleep at all circadian phases.
Sleep. 2001 Aug 1;24(5):565-77. [PMID: 11480654]

Klerman EB, Duffy JF, Dijk DJ, Czeisler CA. Circadian phase resetting in older people by ocular bright light exposure.
J Investig Med. 2001 Jan;49(1):30-40. [PMID: 11217145]

Zeitzer JM, Daniels JE, Duffy JF, Klerman EB, Shanahan TL, Dijk DJ, Czeisler CA. Do plasma melatonin concentrations decline with age?
Am J Med. 1999 Nov;107(5):432-6. [PMID: 10569297]

Czeisler CA, Duffy JF, Shanahan TL, Brown EN, Mitchell JF, Rimmer DW, Ronda JM, Silva EJ, Allan JS, Emens JS, Dijk DJ, Kronauer RE. Stability, precision, and near-24-hour period of the human circadian pacemaker.
Science. 1999 Jun 25;284(5423):2177-81. [PMID: 10381883]

Duffy JF, Dijk DJ, Hall EF, Czeisler CA. Relationship of endogenous circadian melatonin and temperature rhythms to self-reported preference for morning or evening activity in young and older people.
J Investig Med. 1999 Mar;47(3):141-50. [PMID: 10198570]

Duffy JF, Dijk DJ, Klerman EB, Czeisler CA. Later endogenous circadian temperature nadir relative to an earlier wake time in older people.
Am J Physiol. 1998 Nov;275(5 Pt 2):R1478-87. [PMID: 9791064]

Duffy JF, Kronauer RE, Czeisler CA. Phase-shifting human circadian rhythms: influence of sleep timing, social contact and light exposure.
J Physiol. 1996 Aug 15;495 ( Pt 1):289-97. [PMID: 8866371]

Boivin DB, Duffy JF, Kronauer RE, Czeisler CA. Dose-response relationships for resetting of human circadian clock by light.
Nature. 1996 Feb 8;379(6565):540-2. [PMID: 8596632]

Johnson MP, Duffy JF, Dijk DJ, Ronda JM, Dyal CM, Czeisler CA. Short-term memory, alertness and performance: a reappraisal of their relationship to body temperature.
J Sleep Res. 1992 Mar;1(1):24-9. [PMID: 10607021]