Disrupted sleep maintenance is associated with altered circadian phase and phase angle in community-dwelling adults.

OBJECTIVE: We aimed to compare the sleep onset, dim light melatonin onset (DLMO) and phase angle (PA) between sleep onset and DLMO of insomnia patients with those of controls, and to examine the difference in these parameters in relation to objective sleep quality. METHODS: Participants were recruited from three Public Health Centers in Korea. Actigraphy recordings were conducted for seven days. Five hourly saliva samples were obtained from three hours prior to sleep onset. A total of 48 controls and 64 insomnia patients were analyzed. Nocturnal sleep parameters, DLMO, and PA were compared between the controls and insomnia patients, and between the controls and patients with difficulty in maintaining sleep (DMS). These sleep and circadian parameters were compared among the subgroups divided by wake after sleep onset (WASO) amount. RESULTS: There were no significant differences in sleep parameters between the control and insomnia groups, and between the controls and DMS subgroup. The sleep onset, DLMO, and PA of the insomnia group or those of DMS subgroup were not different from those of controls. There were significant differences in the sleep onset and DLMO (p < 0.05) among mild, moderate, and severe WASO groups. A regression analysis revealed the earlier DLMO and shorter PA predicted the severity of WASO (p < 0.0001) in total participants. CONCLUSIONS: Insomnia patients exhibited no difference in their sleep timing and melatonin rhythm compared to controls. However, these circadian parameters varied depending on the severity of WASO, and advanced melatonin phase and its shortened phase angle were associated with worsening of sleep maintenance.

Association of rest-activity and light exposure rhythms with sleep quality in insomnia patients.

The relevance of altered rest-activity rhythm (RAR) and light exposure rhythm (LER) in insomnia patients under natural conditions remains unclear. The aim of this study was to compare the parametric and nonparametric circadian variables of RAR and those of LER under natural conditions between insomnia patients and normal controls (NC) in a community-dwelling setting. The relationship of the nonparametric variables with sleep quality was also explored in both groups. Participants above 18 years old were recruited from three Public Health Centers in a rural area of Korea. Actigraphy (Actiwatch 2; Philips Respironics, Murrysville PA, USA) recording was conducted for 7 days. Subjects were eligible for our study if they had an insomnia disorder (ID) for at least 1 month. Actigraphy data of 78 normal control (NC) subjects (Age, 55.95 ± 13.22 years) and 104 patients with insomnia disorder (ID) (Age, 62.14 ± 12.34 years) were included for the analysis. Acrophases and amplitudes of RAR and LER were estimated using cosinor analysis. Interdaily stability (IS), intradaily variability (IV), and relative amplitude (RA) of these rhythms were determined using nonparametric methods. Parametric cosinor and nonparametric variables of RAR and LER were compared between the NC and ID groups. Generalized linear models (GLMs) were applied to evaluate the main effects of group and each nonparametric variable as well as a group by each variable interaction on the sleep onset latency (SOL), sleep efficiency (SE), and wake after sleep onset (WASO) reflecting sleep quality. Among sleep parameters, the ID group showed significantly lower SE and greater WASO than the NC group. There were no significant differences in the acrophase and amplitude of RAR and LER between the two groups. There were no significant differences in IV, IS, and RA of RAR and LER between the two groups either. GLMs for RAR revealed a significant interaction between the group and IS on the SOL (ß = -46.39, p < 0.01), indicating a negative relationship of the IS with SOL in ID unlike its positive relationship in NC. There were no significant main effects of IV on the SOL, SE, and WASO, but significant main effects of RA on the SE and WASO (ß = 63.65 and ß = -221.43, respectively, p < 0.01). GLMs for LER revealed no significant main effects of IS, IV or RA on the SOL, SE, and WASO, but significant interactions between group and RA on the SE and WASO (ß = 56.17 and ß = -171.93, respectively, p < 0.05), indicating a stronger positive relationship of the RA with SE in ID compared to NC, and a negative relationship of the RA with WASO in ID, unlike its positive relationship in NC. Although our study did not reveal group differences in circadian variables of RAR and LER, it suggested that the regularity of RAR could be positively associated with sleep initiation, while the robustness of LER could be positively associated with sleep maintenance in insomnia patients.

The Epidemiological Studies On The Filariasis In Korea: II. Distribution And Prevalence Of Malayian Filariasis In Southern Korea.

During 1964 to 1967, a survey of 30,534 persons for filariasis was made on all over the country with the following results: 1. Among 24,816 draftees from all over the country in the army recruitment camp 155(0.63 %) were found infected with Brugia malayi. Cheju Do showed the highest microfilaria rate(3.5 %), North Kyongsang Do(1.4 %) the next and South Cholla Do(1.2 %) the third. 2. Blood films from 2,308 inhabitants were examined and 407(17.6 %) showed microfilaria in Cheju Do. 30(3.1 %) out of 974 inhabitants in North Kyongsang Do were found to be infected. The microfilaria rates were 2.0 per cent for 400 inhabitants of Chindo island in South Cholla Do. However, no positive case of microfilaria was found in the inhabitants of Kokumdo among 1,820 persons examined in South Cholla Do and of Namhae island(among 165 persons examined) in South Kyongsang Do. 3. The mean microfilarial density per 20 cu. mm of blood was 52.6 in the inhabitants of Cheju Do, 12.2 in North Kyongsang Do and 27.3 in Chindo island(South Cholla Do). 4. Any distinct relationship between the incidence of positive cases of microfilariae and age or sex of the cases was not observed in Cheju Do. However, in Norh Kyongsang Do and South Cholla Do the microfilaria rate of the male group is higher than the one of the female group of the inhabitants. 5. From the above survey results it turned out that filariasis was found throughout Southern Korea except Kyonggi Do and South Kyongsang Do. A total 30,534 persons examined, 601(2.0 %) were found to be infected by Brugia malayi. Therefore, it seems that there are some endemic foci of malayian filariasis in three main areas such as North Kyongsang Do, South Cholla Do and Cheju Do.