Biomedical subjects

Timothy H Monk

Publications and source records attributed to Timothy H Monk.

21 records · Page 2Linked to original sources

PubMed2002

Masking effects of posture and sleep onset on core body temperature have distinct circadian rhythms: results from a 90-min/day protocol.

Both recumbency and sleep affect core body temperature (CBT). To characterize their circadian effects and interactions, the authors examined the bedtime temperature drops (TDs) of nine men and eight women (aged 20 to 30) who repeated 90-min sleep-wake cycles over 2.5 days. While awake, subjects were exposed to 50 to 250 lux; while asleep, lights were off. Electroencephalogram-monitored time inbed lasted 30 min during each cycle. Cosinor nonlinear mixed-effects regressions modeled the circadian rhythm of TDs. The circadian maximum of TDs occurred approximately 4 h before the time of circadian CBT minimum, in a model that included the effects of baseline expected CBT, deviations from baseline CBT, time in study, and gender-dependent 24- and 12-h adjustments. Rates of temperature drops were faster during initial periods of lying awake than during periods of initially sleeping. Both rates followed separate circadian rhythms. The circadian maximum of TDs was located near customary nocturnal bedtimes, suggesting its role in fostering sleep during a normal bedtime routine. The apparent deceleration of temperature dropping at sleep onset supports the notion that the sleep onset period has complicated circadian neuroregulatory dynamics. These findings confirm the need for nonlinear models of temperature responses to postural changes and sleep that incorporate circadian variability in these masking effects.

Adult↗

PubMedDate not supplied

The daily life of complicated grief patients--what gets missed,what gets added?

Many patients with complicated grief suffer severe symptoms for several years after the loss, interfering with daily life. We sought to determine which elements of a patient's daily routine were likely to be missed or added. Sixty-four patients completed a diary each evening for 2 weeks. The diary asked whether each of 13 daily life activities were done or missed on that day. Comparisons were made with 64 matched healthy control participants. Patients were significantly more likely than controls to miss contact with another person, breakfast, lunch, dinner, starting work, and going outside, and to add a nap and evening snack.

Activities of Daily Living↗

PubMedDate not supplied

Healthy older adults' sleep predicts all-cause mortality at 4 to 19 years of follow-up.

OBJECTIVE: Evidence concerning whether sleep disturbances in older adults predict mortality is mixed. However, data are limited to self-reported sleep problems and may be confounded with other comorbidities. We examined whether electroencephalographic (EEG) sleep parameters predicted survival time independently of known predictors of all-cause mortality. METHODS: A total of 185 healthy older adults, primarily in their 60s through 80s, with no history of mental illness, sleep complaints, or current cognitive impairment, were enrolled in one of eight research protocols between October 1981 and February 1997 that included EEG sleep assessments. At follow-up (mean [SD] = 12.8 [3.7] years after baseline, range = 4.1-19.5), 66 individuals were positively ascertained as deceased and 118 remained alive (total N = 184). RESULTS: Controlling for age, gender, and baseline medical burden, individuals with baseline sleep latencies greater than 30 minutes were at 2.14 times greater risk of death (p =.005, 95% CI = 1.25-3.66). Those with sleep efficiency less than 80% were at 1.93 times greater risk (p =.014, CI = 1.14-3.25). Individuals with rapid eye movement (REM) sleep percentages in the lowest 15% or highest 15% of the total sample's distribution (percentage of REM <16.1 or >25.7) were at 1.71 times greater risk (p =.045, CI = 1.01-2.91). Percentage of slow-wave sleep was associated with time to death at the bivariate level, but not after controlling for potential confounders. CONCLUSIONS: Older adults with specific EEG sleep characteristics have an excess risk of dying beyond that associated with age, gender, or medical burden. The findings suggest that interventions to optimize and protect older adults' sleep initiation, continuity, and quality may be warranted.

Aged↗