Presenting Author:

Alexandra Ritger, B.S.

Principal Investigator:

Phyllis Zee, M.D.

Department:

Neurology, Ken and Ruth Davee Department

Keywords:

acoustic stimulation, slow wave activity, cognitive performance

Location:

Ryan Family Atrium, Robert H. Lurie Medical Research Center

C62 - Clinical

Effect of acoustic stimulation on sleep and cognition

Introduction: Slow wave sleep is important for declarative memory consolidation. Attempts to alter slow wave sleep have focused on pharmacological or behavioral approaches. Previous studies demonstrate that acoustic stimulation during sleep increases slow wave activity (SWA) and improves declarative memory performance particularly when delivered on the upstate of the slow wave. This study aims to determine whether overnight acoustic stimulation pulses, delivered on the upstate of the slow wave using an automated algorithm that tracks real-time electroencephalography (EEG) can increase SWA and improve cognitive outcomes. Methods: Five healthy participants (three female, ages 22-34) completed a randomized, counterbalanced crossover study. The first night of each visit was an adaptation night. On the second night, subjects received either acoustic stimulation through soft headphones during sleep, or sham stimulation (same setup and no sound). An automated system used the midline frontopolar EEG channel to track and deliver acoustic stimulation tailored to each person’s slow waves. The sound (pink or 1/f noise) was delivered in blocks of five pulses (“ON block”), followed by a pause of equal length (“OFF block”). SWA was quantified as delta power in the (0.5-4 Hz) frequency band. For analysis, SWA in ON and OFF blocks was normalized to the total amount of SWA for the duration of all ON and OFF blocks. SWA was assessed by comparing the percent change in SWA in ON blocks compared to OFF bocks. Cognitive outcomes were assessed using a 40 word-pair association task, the psychomotor vigilance task (PVT) to assess speed (1/reaction time), and a Visual Analog Scale for Global Vigor and Affect (VAS-GVA). A two-tailed paired t-test was used to evaluate differences between stimulation and sham conditions. Results: Percent change in SWA in ON blocks compared to OFF blocks was significantly greater in the stimulation condition than the sham condition [Stim: 55.4(12.6)%, Sham: -0.454(1.54)%, p = .011]. VAS vigor was significantly greater in the stimulation condition one hour after wake than the sham condition [Stim: 82.0(8.29)%, Sham: 63.1(3.92)%, p = .040]. There was no difference between groups in the word-pair association task, the PVT, or VAS affect. Discussion: These results demonstrate that automated acoustic stimulation during sleep significantly increases SWA compared to sham. Subjects also reported significantly more vigor in the stimulation condition without any corresponding negative impact on affect. Interestingly despite the improvement in SWA, there is no corresponding increase in objective performance. While preliminary results are promising, increasing the sample size may help elucidate any changes in objective performance.