A review of the recent literature shows the role of caffeine in the physiology, mood, and behavior of persons to be a complex one including changes in arousal, anxiety, and performance. Questions are raised as to what degree the physiological effects of caffeine are due to central nervous system stimulation and/or result from the release of catecholamines. Anxiety resulting from both high levels of caffeine (caffeinism) and caffeine withdrawal plus an association between caffeine and depression are discussed. Performance effects are mixed, with both increases and decreases reported. Effects on mental tasks are related to personality variables. The possible role of differences in initial sensitivity, adaptation to caffeine, and/or interactions with nicotine and alcohol is discussed. The present paper reviews these studies, discusses their implications for both clinical and experimental work, summarizes the major unresolved issues, and makes suggestions for new and continuing areas of research.

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Sixteen infants, comprising two groups of 8 normal neonates each, were reared under one or the other of two different caretaking conditions. Crying, motility and caretaker intervention were monitored for every infant from days 2 to 25 after birth. A monitor variable, "activity-segment time," derived from the continuous record, correlated highly with observed awake time. A significant curvilinear relationship was found for this infant state variable, with highs at the onset and conclusion of the study period regardless of caretaking experience. Differences in rearing environment appear to exert an influence on the degree of day-night differentiation of this variable in the first 10 days of life.In a previous publication (1), a method was described for studying the adaptive process in the neonatal period by means of continuous around-the-clock monitoring of infant activity and caretaking intervention. The institution of a temporal coordination between infant activity and caretaking activity over the 24 hours of the day was illustrated, as well as the use of the method in identifying the day-by-day progress of changes over the first 10 days of life in both infant and caretaking variables. This paper reports a further application of the method over the first 25 days of life as a means of investigating changes in 24-hour distribution of monitor variables correlated with infant sleeping and waking.Essentially the monitor (Figure 1) is a recording bassinet, operating without instrumentation of the baby; it utilizes an Esterline-Angus event recorder moving at 12 inches/hr to record continuously, by separate pens in parallel, several channels of digital inputs. These represent a) small summations of infant activity obtained via an air mattress, strain gauge, amplifier, and integrator system, b) infant crying (occurring while the infant is in the bassinet), c) caretaker's removal of the infant from the bassinet, duration of removal, return of the infant to the bassinet and d) proximity of caretaker to bassinet. Definition of the Variable "ActivitySegment Time"From the record produced (Figure 2), it can be seen that the awakening of an infant from sleep followed by his return to sleep is associated with a sequence of events recorded by the

cially those which describe both changes in infant variables and occurrence of caretaking events over a period of 24 hr. One such study 1 -2 related the crying time of neonates to the occurrence of nursing interventions. In this study the investigators were able to demonstrate a striking reduction in the crying time of infants by a few simple but specific revisions in the nursing schedule which allowed a more immediate nursing response. Focus was upon the characteristics of events in the infant-caretaker interactional system, especially their temporal coordination, rather than upon characteristics of one or the other of the participants. It was a study of the evenness with which an infant's comfort could be maintained over the total 24 hr., day by day, and involved a somewhat different investigative focus than do current studies of the neonatal period.Current investigations of neonatal function or neonate-caretaker interaction tend to rely heavily on relatively brief time-sampled observations. These studies have been aimed at tasks such as the elucidation of cause-effect sequences be-822