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Predictable effects on individual sleep patterns during a rapidly rotating shift system.

J Foret·O Benoit
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Activity CyclesAdultCircadian RhythmHumansIndividualityMaleSleepWorkJournal Article

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J Foret, O Benoit. 1980. Predictable effects on individual sleep patterns during a rapidly rotating shift system.. https://doi.org/10.1007/bf00378095

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Circadian rest-activity disturbances in seasonal affective disorder.

BACKGROUND: Previous studies hypothesized that seasonal affective disorder (SAD) was caused by a circadian rhythm abnormality. The purpose of this study was to ascertain whether rest-activity rhythms were phase delayed, diminished in amplitude, or more poorly entrained to the 24-hour day. METHOD: Twenty healthy adult controls and 25 outpatients meeting Rosenthal-National Institute of Mental Health criteria for SAD and DSM-III-R criteria for major or bipolar depression with seasonal pattern had their levels of activity recorded for 72 hours (weekdays) using wrist-worn actigraphs. RESULTS: Subjects with SAD had activity levels that were 11% lower than controls (P = .03), and their levels of activity were most attenuated during the first 2 hours after arising (P = .004). The relative amplitude of the circadian rhythm did not differ between groups. Patients with SAD were phase delayed by 50 minutes for the entire period (P = .02). Analysis of each individual day indicated that patients were delayed by up to 70 minutes (P = .007). Interdaily stability, an index of coupling between the rhythm and its zeitigeber was reduced in SAD (P = .01). Compared with controls, patients with SAD had best-fit circadian periods that were 92% more deviated from 24 hours (P = .007) and daily acrophase (time of the peak of the fit circadian rhythm) times that were 110% more variable between days (P < .001). CONCLUSIONS: Patients with SAD have circadian rest-activity rhythms that are significantly phase delayed and more poorly entrained to the 24-hour day.

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PubMed1997

Automated analysis of antepartum fetal heart rate in relation to fetal rest-activity states: a longitudinal study of uncomplicated pregnancies using the Sonicaid System 8000.

OBJECTIVES: To learn which fetal heart rate (FHR) parameters change with gestational age and to demonstrate the relation with fetal rest-activity states. STUDY DESIGN: FHR and fetal movements were recorded in 12 uncomplicated pregnancies from 26 weeks gestational age onwards. Seventy-two FHR recordings of 60 min duration were analysed by a computer (Sonicaid System 8000). Statistical analysis of complete 60 min recordings and selective periods of rest and activity comprised Spearman's rank correlation test, regression analysis and Wilcoxon's signed-rank test. RESULTS: The time needed to meet the system's criteria of normality decreased with gestational age. The incidence of accelerations (ACC), overall FHR variation (VAR) and variation during 'episodes of high variation' (VEHV) increased with gestational age in the total population, but statistical significance of these relations could only be demonstrated in a minority of individual fetuses. Most FHR parameters differed significantly for periods of fetal rest and activity. No FHR parameters showed a relation with gestational age during periods of rest. CONCLUSIONS: The increase of ACC, VAR and VEHV with gestational age is primarily due to an increase during fetal activity. The considerable variation within and between fetuses, however, can only be partly explained by fetal rest-activity states.

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PubMed1997

Circadian rest-activity disturbances in children with seasonal affective disorder.

OBJECTIVE: Seasonal affective disorder (SAD) affects from 1.7% to 5.5% of children. Previous studies found that nonseasonally depressed children had a blunted circadian rhythm, while adults with SAD had a delayed and poorly entrained rhythm. The purpose of this study was to determine whether pediatric SAD more closely resembles nonseasonal pediatric depression or adult SAD. METHOD: Twelve normal, healthy volunteers (11.6 +/- 3.7 years; 6 female, 6 male) and 14 unmedicated children with SAD (11.0 +/- 3.3 years; 9 female, 5 male) meeting Rosenthal/NIMH criteria for SAD and Schedule for Affective Disorders and Schizophrenia for School-Age Children-Epidemiologic version criteria for major depression had their levels of activity recorded for 72 hours (weekdays) using belt-worn actigraphs. RESULTS: The SAD group had blunted circadian amplitudes that were 10% lower than normal (p = .004). They were more poorly modeled by the standard cosinor equation (p = .001), and a circadian rhythm accounted for 39% less of the variability in their activity profile (p = .007). The amplitude of the 12-hour harmonic rhythm was markedly increased. There were no differences between SAD and control children in the timing of the circadian rhythm and degree of entrainment. CONCLUSIONS: Children with SAD displayed dysregulated circadian activity rhythms comparable with those reported in nonseasonally depressed children, yet different from those observed in adults.

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