Head Motion Predicts Transient Loss of Consciousness in Human Head Trauma: A Case-Control Study of Mixed Martial Artists.

OBJECTIVE: Concussion with transient loss of consciousness is a commonly observed but poorly understood phenomenon with mounting clinical significance. This study aimed to examine the relationship between head motion in varying planes and transient loss of consciousness in athletes with brain injuries. STUDY DESIGN: A case-control design was used. The Ultimate Fighting Championship database was screened for events ending with knockouts from 2013 to 2016. Time of strike, striking implement, strike location, and head motion were recorded for all knockout strikes (cases) and for a subset of nonknockout strikes (controls). Characteristics of winners and losers were compared using two-tailed t tests. Multivariate logistic regression was used to determine odds ratios for strike characteristics associated with transient loss of consciousness. The Kaplan-Meier estimate was used to describe the temporal distribution of knockouts. RESULTS: One hundred thirty-six fights were identified and 110 videos were included. Head motion in the axial plane was strongly associated with transient loss of consciousness (odds ratio, 45.3; 95% confidence interval, 20.8-98.6). Other predictors of transient loss of consciousness were head motion in sagittal and coronal planes, nonfist striking implements, and strikes to the mandible or maxilla. The Kaplan-Meier survival curve demonstrated a decreasing rate of knockouts through time. CONCLUSIONS: Rotational head acceleration, particularly in the axial plane, is strongly associated with transient loss of consciousness.

Sleep disruption due to hospital noises: a prospective evaluation.

BACKGROUND: Sleep plays a critical role in maintaining health and well-being; however, patients who are hospitalized are frequently exposed to noise that can disrupt sleep. Efforts to attenuate hospital noise have been limited by incomplete information on the interaction between sounds and sleep physiology. OBJECTIVE: To determine profiles of acoustic disruption of sleep by examining the cortical (encephalographic) arousal responses during sleep to typical hospital noises by sound level and type and sleep stage. DESIGN: 3-day polysomnographic study. SETTING: Sound-attenuated sleep laboratory. PARTICIPANTS: Volunteer sample of 12 healthy participants. INTERVENTION: Baseline (sham) night followed by 2 intervention nights with controlled presentation of 14 sounds that are common in hospitals (for example, voice, intravenous alarm, phone, ice machine, outside traffic, and helicopter). The sounds were administered at calibrated, increasing decibel levels (40 to 70 dBA [decibels, adjusted for the range of normal hearing]) during specific sleep stages. MEASUREMENTS: Encephalographic arousals, by using established criteria, during rapid eye movement (REM) sleep and non-REM (NREM) sleep stages 2 and 3. RESULTS: Sound presentations yielded arousal response curves that varied because of sound level and type and sleep stage. Electronic sounds were more arousing than other sounds, including human voices, and there were large differences in responses by sound type. As expected, sounds in NREM stage 3 were less likely to cause arousals than sounds in NREM stage 2; unexpectedly, the probability of arousal to sounds presented in REM sleep varied less by sound type than when presented in NREM sleep and caused a greater and more sustained elevation of instantaneous heart rate. LIMITATIONS: The study included only 12 participants. Results for these healthy persons may underestimate the effects of noise on sleep in patients who are hospitalized. CONCLUSION: Sounds during sleep influence both cortical brain activity and cardiovascular function. This study systematically quantifies the disruptive capacity of a range of hospital sounds on sleep, providing evidence that is essential to improving the acoustic environments of new and existing health care facilities to enable the highest quality of care. PRIMARY FUNDING SOURCE: Academy of Architecture for Health, Facilities Guidelines Institute, and The Center for Health Design.

Covert waking brain activity reveals instantaneous sleep depth.

The neural correlates of the wake-sleep continuum remain incompletely understood, limiting the development of adaptive drug delivery systems for promoting sleep maintenance. The most useful measure for resolving early positions along this continuum is the alpha oscillation, an 8-13 Hz electroencephalographic rhythm prominent over posterior scalp locations. The brain activation signature of wakefulness, alpha expression discloses immediate levels of alertness and dissipates in concert with fading awareness as sleep begins. This brain activity pattern, however, is largely ignored once sleep begins. Here we show that the intensity of spectral power in the alpha band actually continues to disclose instantaneous responsiveness to noise--a measure of sleep depth--throughout a night of sleep. By systematically challenging sleep with realistic and varied acoustic disruption, we found that sleepers exhibited markedly greater sensitivity to sounds during moments of elevated alpha expression. This result demonstrates that alpha power is not a binary marker of the transition between sleep and wakefulness, but carries rich information about immediate sleep stability. Further, it shows that an empirical and ecologically relevant form of sleep depth is revealed in real-time by EEG spectral content in the alpha band, a measure that affords prediction on the order of minutes. This signal, which transcends the boundaries of classical sleep stages, could potentially be used for real-time feedback to novel, adaptive drug delivery systems for inducing sleep.