The purpose of this study was to formulate an algorithm for assessing sleep/waking from activity intensities measured with a waist-worn actigraphy, the Lifecorder PLUS (LC; Suzuken Co. Ltd., Nagoya, Japan), and to test the validity of the algorithm. The study consisted of 31 healthy subjects (M/F = 20/11, mean age 31.7 years) who underwent one night of simultaneous measurement of activity intensity by LC and polysomnography (PSG). A sleep(S)/wake(W) scoring algorithm based on a linear model was determined through discriminant analysis of activity intensities measured by LC over a total of 235 h and 56 min and the corresponding PSG-based S/W data. The formulated S/W scoring algorithm was then used to score S/W during the monitoring epochs (2 min each, 7078 epochs in total) for each subject. The mean agreement rate with the corresponding PSG-based S/W data was 86.9%, with a mean sensitivity (sleep detection) of 89.4% and mean specificity (wakefulness detection) of 58.2%. The agreement rates for the individual stages of sleep were 60.6% for Stage 1, 89.3% for Stage 2, 99.2% for Stage 3 + 4, and 90.1% for Stage REM. These results demonstrate that sleep/wake activity in young to middle-aged healthy subjects can be assessed with a reliability comparable to that of conventional actigraphy through LC waist actigraphy and the optimal S/W scoring algorithm.

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Polysomnographic (PSG) recording of multiple physiological measures remains the gold standard for sleep assessment in both basic and clinical human sleep research. However, PSG requires many unnatural conditions that can influence sleep phenomena. Recently, non-contact sheet sensors (SS) have been developed for sleep evaluation. Sheet sensor technology provides advantages over existing minimally intrusive devices used to analyze sleep-related behavior, such as wrist actigraphy (WA), beginning with freedom from attachment to any probes or devices. Current SS measures additionally include two physiological measures -heart rate (HR) and respiration rate (RR). To test the validity of SS analyses, we performed simultaneous recordings of SS and standard PSG in thirteen healthy adult sleepers, with WA additionally available for nine of the subjects. Sleep period features were compared among the three methods, and HR and RR data from SS and PSG were compared. Comparisons between the automatic scoring of SS and WA and visual PSG scoring showed good sleep-wake discrimination (88.3% and 89.4% respectively). Sleep onset estimation relative to PSG was also good for both SS and WA (0.38 and -2.44 epoch differences, respectively). In addition, HR and RR measured by SS were also compared with PSG. Both HR and RR closely approximated PSG physiological measures (error rates: HR 2.4%, RR 4.3%). In summary, SS is expected to be less disruptive and easier to use for long-term home sleep monitoring.

We describe a handmade eye movement monitor featuring a piezoelectric device for use during transsphenoidal surgery (TSS). The sensor consists of a piezoelectric device, condensers, resistors, and several inexpensive parts. Eyeball movements elicited by surgical manipulations during TSS for cavernous sinus tumor are detected by small disc-shaped sensors taped to the eyelids. The responses could be monitored as sharp waves on an electroencephalograph. After we started using this monitor, both the incidence and the severity of cranial nerve injuries during TSS for cavernous sinus tumor decreased. Our device is especially useful at operations to remove functioning pituitary adenomas invading the cavernous sinus and contributes to their favorable endocrine outcomes. None of our patients manifested the postoperative swelling of the eyelids or conjunctival congestion generally seen in patients subjected to the insertion of needle sensors for the acquisition of electromyograms of the extraocular muscles, which is widely used during surgery to identify the cranial nerves responsible for eye movement. Our monitor is less expensive and easier to use than any commercially available sensor devices. As our method does not require the insertion of needle sensors, it is less invasive than electromyography of the extraocular muscles.

Abstractk-Rhythm appears at the highest amplitude on a bipolar T3-T4 derivation and its frequency range is 7-10 Hz. When a contra-lateral earlobe is used as a reference, the k-rhythm causes serious problems in assessing drowsiness. Assessment of drowsiness using contra-and ipsi-lateral earlobes as references in 129 subjects who showed k-rhythm was compared. Drowsiness could be assessed properly in only 26% of subjects using the contra-lateral earlobe and in 90% of subjects using the ipsi-lateral earlobe. These results suggest that the ear on the ipsi-lateral earlobe should be used as a reference in subjects who show k-rhythm.