• Sleep Medicine and Psychophysiology
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• v.5 no.1
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• pp.111-117
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• 1998

Objectives : 'First-night effect' has been a well-known concept since 1960's. It is important because it is one of the major factors to be considered in assessing the reliability of polysomnographic data. However, 'reverse first-night effect' has also been described, resulting in the inconsistency of conceptualization. We attempted to investigate on the first-night effect in adults by having each of them take two nights of polysomnography in a controlled environment. Young healthy adult volunteers were chosen as subjects in order to rule out age- or health-related confounders. Methods : Polysomnography was performed on eight male medical students (mean $age=23.5\;{\pm}\;0.9$) for two nights with Grass model 78 polysomnograph. We scored manually under the standard protocol each epoch of the sleep records. Sleep variables were obtained and compared between the two nights. Results : Sleep period time(SPT) and total sleep time(TST) of the third fraction of night were significantly longer on the first night than on the second night (p<0.05). However, other sleep variables such as percentage of each sleep stage, sleep latency, REM sleep latency, number of waking, and sleep efficiency were not different between the two nights. Conclusion : We could not confirm the existence of first-night effect in this study. In healthy young male adults, it may not happen at all or may happen to a very negligible degree. Young healthy adults may have more adaptability to a new sleep environment. Also, the provision of a reasonably comfortable sleep environment could have helped them with abolition of first-night effect.

• Sleep Medicine and Psychophysiology
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• v.12 no.1
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• pp.27-31
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• 2005

Objectives: We attempted to compare the performance of 2 commercially available actigraphies with focus on sleep parameters, using polysomnography as standard comparison tool. Methods: Fourteen normal volunteers (5 males and 9 females, mean age of $28{\pm}4.6\;years$) participated in this study. All the participants went through one night of polysomnography, simultaneously wearing 2 different kinds of actigraphies on each wrist. Polysomnographic and actigraphic data were stored, downloaded, and processed according to standard protocols and then statistically compared. Results: Both $ActiWatch^{(R)}$ and $SleepWatch^{(R)}$ tended to overestimate the total sleep time, compared to the polysomnography. $SleepWatch^{(R)}$ tended to underestimate the sleep latency. The two actigraphs and the polysomnograph did not show significant difference of sleep efficiency, when compared with one another. In addition, all of the sleep parameters from the instruments showed linear correlations except in $SleepWatch^{(R)}'s$ sleep latency. The sleep parameters from the two actigraphs did not show much noteworthy difference, and linear relationships were found between the sleep parameters from the two actigraphs. There was no significant distinction in the results of the two different actigraphs. Conclusion: The results of two actigraphies can be used interchangeably since the sleep parameters of the two different actigraphies do not show significant differences statistically. Overall, it is not legitimate to use actigraphy as a substitute for polysomnography. However, since sleep parameters except sleep latency show linear correlations, actigraphy might possibly be used to follow up patients after polysomnography.

• Sleep Medicine and Psychophysiology
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• v.14 no.1
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• pp.20-25
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• 2007

The present study compared the actigraphic indices between both wrist actigraphies (WATGs), and the sleep estimates between each WATG and nocturnal polysomnography (NPSG) to assess their differences and consistencies. We studied 22 right-handed subjects (mean age $43.9{\pm}13.3\;years$, M：F=14：8) with untreated primary sleep disorders (primary insomnia=8, simple snorer=2, obstructive sleep apnea=12) undergone by overnight both WATGs and NPSG, simultaneously. Comparison and correlation were analyzed between right and left wrist actigraphic data. In the sleep estimates of both WATGs and NPSG, each WATG was compared and correlated with NPSG in sleep period time (SPT), total sleep time (TST), sleep latency (SL), sleep efficiency (SE) and wake time (WT). Sleep indices between both WATGs showed significant positive correlations with no correlations in SL and fragmentation index (FI). There were no differences in sleep indices between both WATGs. SPTs of both WATGs, SL of left WATG, and TST of right WATG showed positively significant correlations, and SE of right WATG did negatively significant correlation in sleep indices between each WATG and NPSG. As each WATG was compared to PSG, SPTs of both WATGs and WT of right WATG were decreased, and TST and SE of right WATG and SL of left WATG were increased. Inconsistent SL and FI between both WATGs indicate that the activities between both WATGs can differentially happen during wake or arousal. Inconsistent sleep estimates between each WATG and NPSG may indicate the limited usefulness in measuring and analyzing one-night sleep by using WATG.