Later endogenous circadian temperature nadir relative  to an earlier wake time in older people

The contribution of the circadian timing system to the age-related advance of sleep-wake timing was investigated in two experiments. In a constant routine protocol, we found that the average wake time and endogenous circadian phase of 44 older subjects were earlier than that of 101 young men. However, the earlier circadian phase of the older subjects actually occurred later relative to their habitual wake time than it did in young men. These results indicate that an age-related advance of circadian phase cannot fully account for the high prevalence of early morning awakening in healthy older people. In a second study, 13 older subjects and 10 young men were scheduled to a 28-h day, such that they were scheduled to sleep at many circadian phases. Self-reported awakening from scheduled sleep episodes and cognitive throughput during the second half of the wake episode varied markedly as a function of circadian phase in both groups. The rising phase of both rhythms was advanced in the older subjects, suggesting an age-related change in the circadian regulation of sleep-wake propensity. We hypothesize 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. This earlier exposure to light 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.

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Sleep in Normal Aging, Homeostatic and Circadian Regulation and Vulnerability to Sleep Deprivation

Brain Sciences ◽

10.3390/brainsci11081003 ◽

2021 ◽

Vol 11 (8) ◽

pp. 1003

Author(s):

Jacques Taillard ◽

Claude Gronfier ◽

Stéphanie Bioulac ◽

Pierre Philip ◽

Patricia Sagaspe

Keyword(s):

Older Adults ◽

Sleep Deprivation ◽

Health Management ◽

Nrem Sleep ◽

Early Morning ◽

Subcortical Structures ◽

Wake Time ◽

Adverse Health Outcomes ◽

Neurobehavioral Function ◽

Age Related

In the context of geriatric research, a growing body of evidence links normal age-related changes in sleep with many adverse health outcomes, especially a decline in cognition in older adults. The most important sleep alterations that continue to worsen after 60 years involve sleep timing, (especially early wake time, phase advance), sleep maintenance (continuity of sleep interrupted by numerous awakenings) and reduced amount of sigma activity (during non-rapid eye movement (NREM) sleep) associated with modifications of sleep spindle characteristics (density, amplitude, frequency) and spindle–Slow Wave coupling. After 60 years, there is a very clear gender-dependent deterioration in sleep. Even if there are degradations of sleep after 60 years, daytime wake level and especially daytime sleepiness is not modified with age. On the other hand, under sleep deprivation condition, older adults show smaller cognitive impairments than younger adults, suggesting an age-related lower vulnerability to extended wakefulness. These sleep and cognitive age-related modifications would be due to a reduced homeostatic drive and consequently a reduced sleep need, an attenuation of circadian drive (reduction of sleep forbidden zone in late afternoon and wake forbidden zone in early morning), a modification of the interaction of the circadian and homeostatic processes and/or an alteration of subcortical structures involved in generation of circadian and homeostatic drive, or connections to the cerebral cortex with age. The modifications and interactions of these two processes with age are still uncertain, and still require further investigation. The understanding of the respective contribution of circadian and homeostatic processes in the regulation of neurobehavioral function with aging present a challenge for improving health, management of cognitive decline and potential early chronobiological or sleep-wake interventions.

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Prediction Of Shiftworker Alertness, Sleep, And Circadian Phase Using A Model Of Arousal Dynamics Constrained By Shift Schedules And Light Exposure

SLEEP ◽

10.1093/sleep/zsab146 ◽

2021 ◽

Author(s):

Stuart A Knock ◽

Michelle Magee ◽

Julia E Stone ◽

Saranea Ganesan ◽

Megan D Mulhall ◽

...

Keyword(s):

Light Exposure ◽

Night Shift ◽

Vigilance Task ◽

Study Data ◽

Accurate Prediction ◽

Environmental Constraints ◽

Wake Time ◽

Circadian Phase ◽

Shift Schedules ◽

And Performance

Abstract Study Objectives The study aimed to, for the first time, (i) compare sleep, circadian phase, and alertness of Intensive Care Unit (ICU) nurses working rotating shifts with those predicted by a model of arousal dynamics; and (ii) investigate how different environmental constraints affect predictions and agreement with data. Methods The model was used to simulate individual sleep-wake cycles, urinary 6-sulphatoxymelatonin (aMT6s) profiles, subjective sleepiness on the Karolinska Sleepiness Scale (KSS), and performance on a Psychomotor Vigilance Task (PVT) of 21 ICU nurses working day, evening, and night shifts. Combinations of individual shift schedules, forced wake time before/after work and lighting, were used as inputs to the model. Predictions were compared to empirical data. Simulations with self-reported sleep as an input were performed for comparison. Results All input constraints produced similar prediction for KSS, with 56-60% of KSS scores predicted within ±1 on a day and 48-52% on a night shift. Accurate prediction of an individual’s circadian phase required individualised light input. Combinations including light information predicted aMT6s acrophase within ±1 h of the study data for 65% and 35-47% of nurses on diurnal and nocturnal schedules. Minute-by-minute sleep-wake state overlap between the model and the data was between 81±6% and 87±5% depending on choice of input constraint. Conclusions The use of individualised environmental constraints in the model of arousal dynamics allowed for accurate prediction of alertness, circadian phase and sleep for more than half of the nurses. Individual differences in physiological parameters will need to be accounted for in the future to further improve predictions.

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Circadian Phase Resetting in Older People by Ocular Bright Light Exposure

Journal of Investigative Medicine ◽

10.2310/6650.2001.34088 ◽

2001 ◽

Vol 49 (1) ◽

pp. 30-40 ◽

Cited By ~ 54

Author(s):

E.B. Klerman ◽

J.F. Duffy ◽

D.-J. Dijk ◽

C.A. Czeisler

Keyword(s):

Older People ◽

Light Exposure ◽

Bright Light ◽

Phase Resetting ◽

Circadian Phase ◽

Bright Light Exposure

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Daily exercise facilitates phase delays of circadian melatonin rhythm in very dim light

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.00397.2003 ◽

2004 ◽

Vol 286 (6) ◽

pp. R1077-R1084 ◽

Cited By ~ 111

Author(s):

Laura K. Barger ◽

Kenneth P. Wright ◽

Rod J. Hughes ◽

Charles A. Czeisler

Keyword(s):

Exercise Intervention ◽

Light Exposure ◽

Phase Relationship ◽

Shift Workers ◽

Circadian Phase ◽

Daily Exercise ◽

Timing System ◽

Before And After ◽

Circadian Timing System ◽

Dim Light

Shift workers and transmeridian travelers are exposed to abnormal work-rest cycles, inducing a change in the phase relationship between the sleep-wake cycle and the endogenous circadian timing system. Misalignment of circadian phase is associated with sleep disruption and deterioration of alertness and cognitive performance. Exercise has been investigated as a behavioral countermeasure to facilitate circadian adaptation. In contrast to previous studies where results might have been confounded by ambient light exposure, this investigation was conducted under strictly controlled very dim light (standing ∼0.65 lux; angle of gaze) conditions to minimize the phase-resetting effects of light. Eighteen young, fit males completed a 15-day randomized clinical trial in which circadian phase was measured in a constant routine before and after exposure to a week of nightly bouts of exercise or a nonexercise control condition after a 9-h delay in the sleep-wake schedule. Plasma samples collected every 30–60 min were analyzed for melatonin to determine circadian phase. Subjects who completed three 45-min bouts of cycle ergometry each night showed a significantly greater shift in the dim light melatonin onset (DLMO25%), dim light melatonin offset, and midpoint of the melatonin profile compared with nonexercising controls (Student t-test; P < 0.05). The magnitude of phase delay induced by the exercise intervention was significantly dependent on the relative timing of the exercise after the preintervention DLMO25% ( r = −0.73, P < 0.05) such that the closer to the DLMO25%, the greater the phase shift. These data suggest that exercise may help to facilitate circadian adaptation to schedules requiring a delay in the sleep-wake cycle.

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Clinical pharmacology of analgesics in old age and frailty

Reviews in Clinical Gerontology ◽

10.1017/s0959259809990232 ◽

2009 ◽

Vol 19 (2) ◽

pp. 103-118 ◽

Cited By ~ 12

Author(s):

Sarah J Mitchell ◽

Sarah N Hilmer ◽

Andrew J McLachlan

Keyword(s):

Clinical Pharmacology ◽

Older People ◽

Old Age ◽

Pain Control ◽

Individual Variability ◽

Rational Basis ◽

Pharmacokinetics And Pharmacodynamics ◽

Age Related ◽

High Prevalence ◽

Prevalence Of Pain

SummaryThere is a high prevalence of pain in older people. Optimal assessment and management of pain in this population is challenging. The pharmacokinetics and pharmacodynamics of analgesic medications are affected by ageing and frailty, as well as by intercurrent medical conditions and their treatments. This review describes what is currently understood about the impacts of old age and frailty on the clinical pharmacology of commonly used analgesics, to provide a rational basis for the use of these medicines. In view of the wide age-related inter-individual variability in pharmacokinetics and pharmacodynamics of analgesic medications, monitoring of clinical response and adverse effects is essential to optimize pain control in older people.

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Age-Related Differences in Processing Dynamic Information to Identify Vowel Quality

Journal of Speech Language and Hearing Research ◽

10.1044/jshr.3504.892 ◽

1992 ◽

Vol 35 (4) ◽

pp. 892-902 ◽

Cited By ~ 16

Author(s):

Robert Allen Fox ◽

Lida G. Wall ◽

Jeanne Gokcen

Keyword(s):

Older Adults ◽

Vowel Quality ◽

Perceptual Cues ◽

Dynamic Information ◽

Process Dynamic ◽

Center Condition ◽

Age Related ◽

Control Version ◽

Older Subjects ◽

Whole Word

This study examined age-related differences in the use of dynamic acoustic information (in the form of formant transitions) to identify vowel quality in CVCs. Two versions of 61 naturally produced, commonly occurring, monosyllabic English words were created: a control version (the unmodified whole word) and a silent-center version (in which approximately 62% of the medial vowel was replaced by silence). A group of normal-hearing young adults (19–25 years old) and older adults (61–75 years old) identified these tokens. The older subjects were found to be significantly worse than the younger subjects at identifying the medial vowel and the initial and final consonants in the silent-center condition. These results support the hypothesis of an age-related decrement in the ability to process dynamic perceptual cues in the perception of vowel quality.

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The Biological Clock and Sleep in the Elderly

Zeitschrift für Gerontopsychologie & -psychiatrie ◽

10.1024/1011-6877.19.1.45 ◽

2006 ◽

Vol 19 (1) ◽

pp. 45-51 ◽

Cited By ~ 1

Author(s):

Myriam Juda ◽

Mirjam Münch ◽

Anna Wirz-Justice ◽

Martha Merrow ◽

Till Roenneberg

Keyword(s):

Circadian Rhythms ◽

Biological Clock ◽

The Elderly ◽

Early Morning ◽

Behavioral Changes ◽

Older Age ◽

Age Related ◽

Theoretical Considerations ◽

Sleep Difficulties ◽

Circadian Biology

Abstract: Among many other changes, older age is characterized by advanced sleep-wake cycles, changes in the amplitude of various circadian rhythms, as well as reduced entrainment to zeitgebers. These features reveal themselves through early morning awakenings, sleep difficulties at night, and a re-emergence of daytime napping. This review summarizes the observations concerning the biological clock and sleep in the elderly and discusses the documented and theoretical considerations behind these age-related behavioral changes, especially with respect to circadian biology.

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Rational Use of Protein Supplements in the Elderly—Relevance of Gastrointestinal Mechanisms

Nutrients ◽

10.3390/nu13041227 ◽

2021 ◽

Vol 13 (4) ◽

pp. 1227

Author(s):

Ian Chapman ◽

Avneet Oberoi ◽

Caroline Giezenaar ◽

Stijn Soenen

Keyword(s):

Blood Glucose ◽

Older People ◽

The Elderly ◽

Time Intervals ◽

Lower Blood Glucose ◽

Protein Supplements ◽

Protein Requirements ◽

Lower Blood ◽

Older Subjects

Protein supplements are increasingly used by older people to maintain nutrition and prevent or treat loss of muscle function. Daily protein requirements in older people are in the range of 1.2 gm/kg/day or higher. Many older adults do not consume this much protein and are likely to benefit from higher consumption. Protein supplements are probably best taken twice daily, if possible soon after exercise, in doses that achieve protein intakes of 30 gm or more per episode. It is probably not important to give these supplements between meals, as we have shown no suppressive effects of 30 gm whey drinks, and little if any suppression of 70 gm given to older subjects at varying time intervals from meals. Many gastrointestinal mechanisms controlling food intake change with age, but their contributions to changes in responses to protein are not yet well understood. There may be benefits in giving the supplement with rather than between meals, to achieve protein intakes above the effective anabolic threshold with lower supplement doses, and have favourable effects on food-induced blood glucose increases in older people with, or at risk of developing, type 2 diabetes mellitus; combined protein and glucose drinks lower blood glucose compared with glucose alone in older people.

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