Stability, precision, and near-24-hour period of the human circadian pacemaker.
- C. Czeisler, J. Duffy, R. Kronauer
- 25 June 1999
Estimation of the periods of the endogenous circadian rhythms of melatonin, core body temperature, and cortisol in healthy young and older individuals living in carefully controlled lighting conditions has revealed that the intrinsic period of the human circadian pacemaker averages 24.18 hours in both age groups, with a tight distribution consistent with other species.
Bright light induction of strong (type 0) resetting of the human circadian pacemaker.
- C. Czeisler, R. Kronauer, J. Ronda
- Psychology, BiologyScience
- 16 June 1989
The data indicate that the sensitivity of the human circadian pacemaker to light is far greater than previously recognized and have important implications for the therapeutic use of light in the management of disorders of circadian regulation.
Relationship of endogenous circadian melatonin and temperature rhythms to self-reported preference for morning or evening activity in young and older people.
- J. Duffy, D. Dijk, E. F. Hall, C. Czeisler
- PsychologyJournal of Investigative Medicine
- 1 March 1999
An association between circadian phase, the relationship between the sleep-wake cycle and circadianphase, and morningness-eveningness in young adults is demonstrated and age-related changes in phase angle cannot be attributed fully to an age- related shift toward morningness.
Sex difference in the near-24-hour intrinsic period of the human circadian timing system
- J. Duffy, S. Cain, C. Czeisler
- Biology, PsychologyProceedings of the National Academy of Sciences…
- 2 May 2011
The average intrinsic period of the melatonin and temperature rhythms in this population was very close to 24 h, but the intrinsic circadian period observed in women was significantly shorter, which may have implications for understanding sex differences in habitual sleep duration and insomnia prevalence.
Association of intrinsic circadian period with morningness-eveningness, usual wake time, and circadian phase.
- J. Duffy, D. W. Rimmer, C. Czeisler
- PsychologyBehavioral Neuroscience
- 1 August 2001
A chronobiological mechanism by which the biological clock of morning types may be set to an earlier hour is explored, demonstrating that a fundamental property of the circadian pacemaker is correlated with the behavioral trait of morningness-eveningness.
Later endogenous circadian temperature nadir relative to an earlier wake time in older people.
- J. Duffy, D. Dijk, E. Klerman, C. Czeisler
- PsychologyAmerican Journal of Physiology
- 1 November 1998
It is hypothesized that under entrained conditions, these age-related changes in the relationship between circadian phase and wake time are likely associated with self-selected light exposure at an earlier circadian phase, which could account for the earlier clock hour to which the endogenous circadian pacemaker is entrained in older people and thereby further increase their propensity to awaken at an even earlier time.
Evening use of light-emitting eReaders negatively affects sleep, circadian timing, and next-morning alertness
- A. Chang, D. Aeschbach, J. Duffy, C. Czeisler
- PsychologyProceedings of the National Academy of Sciences…
- 22 December 2014
It is found that the use of portable light-emitting devices immediately before bedtime has biological effects that may perpetuate sleep deficiency and disrupt circadian rhythms, both of which can have adverse impacts on performance, health, and safety.
Circadian and sleep/wake dependent aspects of subjective alertness and cognitive performance
- D. Dijk, J. Duffy, C. Czeisler
- Psychology, BiologyJournal of Sleep Research
- 1 June 1992
It was revealed that prior wakefulness within a range of 0–18 h significantly reduced alertness and performance and that the circadian rhythm of core body temperature paralleled the circadian Rhythm of alerts and performance.
Entrainment of the Human Circadian System by Light
An integrated perspective on circadian entrainment in humans is provided with respect to recent advances in the authors' knowledge of circadian period and of the effects of light on the biological clock in humans.
Ageing and the circadian and homeostatic regulation of human sleep during forced desynchrony of rest, melatonin and temperature rhythms
- D. Dijk, J. Duffy, E. Riel, T. Shanahan, C. Czeisler
- Biology, PsychologyJournal of Physiology
- 1 April 1999
Age‐related decrements in sleep consolidation and increased susceptibility to circadian phase misalignment in older people appear to be related to the interaction between a reduction in the homeostatic drive for sleep and a reduced strength of the circadian signal promoting sleep in the early morning.