Arousal from sleep: the differential effect of frequencies equated for loudness

The present research required individual subjects to personally equate the loudness of three different auditory frequencies. When these same auditory stimuli were presented to the subject during sleep they produced equal levels of arousal (increases in cortical desynchronization) during sleep characterized by nonREM fast-wave EEG activity but different levels of arousal during sleep characterized by slow-wave EEG activity. During this latter type of sleep, the individual's arousal appeared more related to physical sound pressure level than subjective loudness. These results are discussed in relation to the possible occurrence of cortical inhibition during sleep characterized by slow-wave electrocortical activity.     

The wrist is not the brain: Estimation of sleep by clinical and consumer wearable actigraphy devices is impacted by multiple patient‐ and device‐specific factors

Clinical actigraphy devices provide adequate estimates of some sleep measures across large groups. In practice, providers are asked to apply clinical or consumer wearable data to individual patient assessments. Inter‐individual variability in device performance will impact such patient‐specific interpretation. We assessed two devices, clinical and consumer, to determine the magnitude and predictors of this individual‐level variability. One hundred and two patients (55 [53.9%] female; 56.4 [±16.3] years old) undergoing polysomnography wore Jawbone UP3 and/or Actiwatch2. Device total sleep time, sleep efficiency, wake after sleep onset and sleep latency were compared with polysomnography. Demographics, sleep architecture and clinical measures were compared to device performance. Actiwatch overestimated total sleep time by 27.2 min (95% confidence limits [CL], 138.3 min over to 84.0 under), overestimated sleep efficiency by 6.8% (95% CL, 34.1% over to 20.5% under), overestimated sleep onset latency by 2.6 min (95% CL, 63.3 over to 58.2 under) and underestimated wake after sleep onset by 50.7 min (95% CL, 162.5 under to 61.2 over). Jawbone overestimated total sleep time by 59.1 min (95% CL, 208.6 min over to 90.5 under) and overestimated sleep efficiency by 14.9% (95% CL, 52.6% over to 22.7% under). In multivariate models, age, sleep onset latency, wake after sleep onset, % N1 and apnea–hypopnea index explained only some of the variance in device performance. Gender also affected performance. Actiwatch and Jawbone mis‐estimate sleep measures with very wide confidence limits and accuracy varies with multiple patient‐level characteristics. Given these large individual inaccuracies, data from these devices must be applied only with extreme caution in clinical practice.     

The crossed-uncrossed difference in simple reaction times to lateralized auditory stimuli is not a measure of interhemispheric transmission time: evidence from the split brain

In a complete commissurotomy patient, the difference in simple (detection) reaction times between responses to contralateral and ipsilateral auditory stimuli was found to be small (less than 5 ms) and not reliable, whereas the difference between contralateral and ipsilateral responses to lateralized visual stimuli was found to be large (ranging from 25 ms to 45 ms in different previous studies) and always reliable. This suggests that the reaction times difference in detecting lateralized auditory stimuli is not a valid estimate of interhemispheric transmission time. Received: 20 November, 1998 / Accepted: 21 April, 1999