Sleep Med Psychophysiol.  1998 Jun;5(1):111-117.

Investigation of 'First-Night Effect' in Normal Young Adult Male Subjects on Polysomnography

• Kim EJ
• Jeong DU

Abstract

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+/-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.

Keyword

First-night effect; sleep environment; adaptation; polysomnography; young healthy adults

MeSH Terms

Adult
Environment, Controlled
Humans
Male*
Poaceae
Polysomnography*
Sleep Stages
Sleep, REM
Students, Medical
Volunteers
Young Adult*