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Brain Science for Humankind.

RYTHM & DREEM

At Rythm, we believe that combining fundamental neurosciences and advanced technologies will bring unprecedented and

powerful solutions to improve people’s wellbeing, performance and health.

We have started with one of the biggest modern challenge : Sleep. Dreem is the first active sleep platform that will allow

people to improve sleep efficiently.

BAD SLEEP IS A MODERN SCOURGE

1/3of the global population is suffering from poor sleep quality, leading to disastrous effects on health, cognitive and physical performances.

Stress Work Environment Pathologies

13M People using benzodiazepine in FR $100b Annual cost of bad

sleep in the USA.

…AND A COMPLEX PROBLEM WITH NO SOLUTION

Sleep Centers and Drugs.MEDICAL CONSUMER

Wearables, Apps, Smarthome.

For Sleep Centers: lack of resources, very low attending, and expensive.

For Drugs: addictive, side effects and non individualized.

Consumer devices lack of accuracy and are not active which lead to very low

results on improvement and usage drops of these devices.

There is a need for an individualized and active solution to answer efficiently the various sleep challenges.

BRAIN IS KEY

The last decades of research in neurosciences bring powerful solutions to understand and improve sleep.

SLEEP, Vol. 37, No. 6, 2014 1143 Hypnotic Suggestions Deepen Sleep—Cordi et al.

INTRODUCTIONSleep disturbances are highly common and present a major

challenge for modern societies. Disturbed and insufficient sleep is strongly associated with several major diseases including hypertension, cardiovascular disease, obesity, depression, anxiety, bipolar disorders, and Alzheimer disease.1–6 In partic-ular, slow wave sleep (SWS) has proven vital for health and well-being, and slow wave activity (SWA) during SWS bene-fits both the immune system as well as cognitive functions and brain plasticity.7–11 Importantly, both the amount of SWS and SWA are strongly reduced across the lifespan, and the reduc-tion in SWS has been linked to age-related prefrontal brain atrophy and memory impairments.12,13 Furthermore, frequently prescribed sleep-inducing drugs typically hinder the occurrence of SWS, lose their efficacy during long-term treatment, have adverse side effects, and often are associated with a high risk of addiction.14,15 Thus, the development of efficient and risk-free approaches to improve sleep and particularly SWS are highly warranted.

One nonpharmacological approach to improve sleep is hypnosis.16–18 Although there are different definitions of

DEEPENING SLEEP BY HYPNOTIC SUGGESTIONhttp://dx.doi.org/10.5665/sleep.3778

Deepening Sleep by Hypnotic SuggestionMaren J. Cordi, Dipl Psych1; Angelika A. Schlarb, PhD2; Björn Rasch, PhD1,3,4

1University of Zurich, Institute of Psychology, Division of Biopsychology, Zurich, Switzerland, Binzmühlestrasse 14/5, 8050 Zürich; 2University of Tübingen, Department of Psychology, Division of Clinical Psychology and Psychotherapy, Tübingen, Germany; 3Zurich Center for Interdisciplinary Sleep Research (ZiS), University of Zurich, Zurich, Switzerland; 4University of Fribourg, Department of Psychology, Division of Cognitive Biopsychology and Methods, Fribourg, Switzerland

Submitted for publication July, 2013Submitted in final revised form February, 2014Accepted for publication February, 2014Address correspondence to: Björn Rasch, University of Fribourg, Departe-ment of Psychology, Division of Biopsychology and Methods, Rue P.A. de Faucigny 2, 1701Fribourg, Switzerland; Tel: +41 26 300 7637; Fax: +41 26 300 9712; E-mail: bjoern.rasch@unifr.ch

Study Objectives: Slow wave sleep (SWS) plays a critical role in body restoration and promotes brain plasticity; however, it markedly declines across the lifespan. Despite its importance, effective tools to increase SWS are rare. Here we tested whether a hypnotic suggestion to “sleep deeper” extends the amount of SWS.Design: Within-subject, placebo-controlled crossover design.Setting: Sleep laboratory at the University of Zurich, Switzerland.Participants: Seventy healthy females 23.27 ± 3.17 y.Intervention: Participants listened to an auditory text with hypnotic suggestions or a control tape before napping for 90 min while high-density electroencephalography was recorded.Measurements and Results: After participants listened to the hypnotic suggestion to “sleep deeper” subsequent SWS was increased by 81% and time spent awake was reduced by 67% (with the amount of SWS or wake in the control condition set to 100%). Other sleep stages remained unaffected. Additionally, slow wave activity was significantly enhanced after hypnotic suggestions. During the hypnotic tape, parietal theta power increases predicted the hypnosis-induced extension of SWS. Additional experiments confirmed that the beneficial effect of hypnotic suggestions on SWS was specific to the hypnotic suggestion and did not occur in low suggestible participants.Conclusions: Our results demonstrate the effectiveness of hypnotic suggestions to specifically increase the amount and duration of slow wave sleep (SWS) in a midday nap using objective measures of sleep in young, healthy, suggestible females. Hypnotic suggestions might be a successful tool with a lower risk of adverse side effects than pharmacological treatments to extend SWS also in clinical and elderly populations.Keywords: high-density EEG, hypnosis, sleep, slow wave sleepCitation: Cordi MJ, Schlarb AA, Rasch B. Deepening sleep by hypnotic suggestion. SLEEP 2014;37(6):1143-1152.

hypnosis, Oakley and Halligan19 define hypnosis as a state of changed mental activity after an induction procedure that mainly encompasses a state of focused attention and absorp-tion. Importantly, during the state of hypnosis, suggestible subjects respond more easily to hypnotic suggestions, which are statements given during induction or afterwards, intended to change or influence behavior. They can include decrease of pain, motor paralysis, or posthypnotic amnesia, and recent cognitive neuroscience research has successfully demonstrated effects of these suggestions on underlying brain activation using objective neuroimaging methods.20–25 In therapeutical contexts, hypnosis has been proven an effective tool in reducing pain, anxiety, and stress-related disorders,26,27 and several studies provide evidence for a beneficial effect of hypnosis on sleep disturbances and insomnias.16–18 However, most of these studies are either case reports or include only subjective measures of sleep quality, whereas well-controlled experimental studies including objective sleep parameters and standard polysom-nography are lacking.28 In particular, no study has ever tested whether hypnotic suggestions are effective in increasing objec-tive measures of sleep, like the amount of SWS or SWA. And finally, the possibility to induce SWS by hypnotic suggestions would be highly relevant in clinical terms as well as for healthy aging.

Here we tested whether a hypnotic suggestion to “sleep deeper” increases the amount of SWS and SWA using high-density electroencephalographic (EEG) recordings in a sleep laboratory (experiment 1). We show that the hypnotic sugges-tion increases the amount of SWS and SWA during a midday nap in healthy, nonhabitual nappers suggestible to hypnosis

Industrial Health, 1993, 31, 35-38 35

Sleep Induction Effects of Steady 60 dB (A)Pink Noise

Abstract : The effects of 60 dB (A) steady pink noise on sleep induction were studied. Two experiments were conducted. First, 10 night-sleep polygrams of a young male subject were recorded consecutively as controls. Five night polygrams of the same subject were then recorded with exposure to steady 60 dB (A) pink noise. Second, polygrams of four students were recorded using the same noise exposure as in the first experiment. Polygrams for the control night were also recorded. Noise exposure tended to shorten sleep latency, i.e., the values were 4.2 and 9.5 min in the first and second experiment, respectively. The steady 60 dB (A) noise made sleep induction easier.

Key words: Steady pink noise—-Sleep latency—-Insomnia

Environmental noise is a major cause of sleep disturbance, though passengers in trains or airplanes often sleep well in noisy environments. Eberhardt et al.1) made a comparison of steady and intermittent road traffic noise on sleep. They found that 45 dB (A) steady noise caused a REM sleep deficit, while 45 dB (A) intermittent noise caused sleep stage 3 and 4 deficits, and that 55 dB (A) noise led to awakening. We have already reported the sleep induction effects of steady pink noise in a case study2). This article focuses on the effects of the same 60 dB (A) pink noise on the shortening of sleep latency, adding four other young subjects.

MATERIAL AND METHODS

The first experiment was conducted on a healthy male subject 28 years of age (A)2). The second experiment was performed on four students, three males (B

—D) and one female (E) , aged 19 to 21 years. Their sleep polygrams were recorded during all-night exposure to the same sound. Polygrams on the control night were also recorded with a background level of 33 to 37 dB (A). Alcoholic beverages and drug ingestion were prohibited during the experiment. The steady 60 dB (A) pink noise used in an experimental room was produced by an SF-05 noise generator (RION Co. Ltd., Tokyo). Pink noise was defined as follows : the correction of white noise by making sound pressure level of each frequency band to be constant. Pink noise is more similar to truck and bus noise than white noise. The pink noise was delivered through a loudspeaker located 2 m from the head of the subject at the same height from the floor. The microphone of a NA —23 sound level meter (RION Co. Ltd., Tokyo) was positioned 0.3 m from the head of the subject. Electroencephalogram (EEG) leads were positioned accord-ing to the international 10-20 method (C3-A2). The EEG, electromyogram

Reduction in Time-to-Sleep through EEG BasedBrain State Detection and Audio Stimulation

Zhuo Zhang1, Cuntai Guan1, Ti Eu Chan1, Juanhong Yu1, Aung Aung Phyo Wai1, Chuanchu Wang1, Haihong Zhang1

ABSTRACT

We developed an EEG- and audio-based sleep sens-ing and enhancing system, called iSleep (interactive Sleepenhancement apparatus). The system adopts a closed-loopapproach which optimizes the audio recording selectionbased on user’s sleep status detected through our online EEGcomputing algorithm. The iSleep prototype comprises twomajor parts: 1) a sleeping mask integrated with a single chan-nel EEG electrode and amplifier, a pair of stereo earphonesand a microcontroller with wireless circuit for control anddata streaming; 2) a mobile app to receive EEG signals foronline sleep monitoring and audio playback control. In thisstudy we attempt to validate our hypothesis that appropriateaudio stimulation in relation to brain state can induce fasteronset of sleep and improve the quality of a nap. We conductexperiments on 28 healthy subjects, each undergoing twonap sessions - one with a quiet background and one withour audio-stimulation. We compare the time-to-sleep in bothsessions between two groups of subjects, e.g., fast and slowsleep onset groups. The p-value obtained from WilcoxonSigned Rank Test is 1.22e− 04 for slow onset group, whichdemonstrates that iSleep can significantly reduce the time-to-sleep for people with difficulty in falling sleep.

I. BACKGROUND

Studies have shown that soothing audio stimulation canhelp to improve the quality of sleep in nearly all agegroups [1]–[4]. A study conducted by Johnson in 2003[5] suggests that music is beneficial for people with sleep(onset) problems as it can decrease the frustration and dreadassociated with sleep complaints. Since the application ofmusic intervention does not involve extensive investments intraining or tools, it is relatively inexpensive, portable andreadily available to the masses [6]. In 2009, de Niet et al.[7] conducted a survey about the efficacy of audio as aform of sleep-promoting intervention. The authors performedmeta-analysis of data from previous research findings andconcluded that music-assisted relaxation had a moderateeffect on the sleep quality of patients with sleep complaints.Most studies on music-induced sleep have focused mainlyon patients with sleep problems. The assessments of sleepquality have been based mainly on feedback from patients,subjects or care givers. To the best of our knowledge, thereis few studies quantify the effectiveness of audio stimulationin terms of promoting sleep onset in the healthy population.

1Institute for Infocomm Research, 1 Fusionopolis Way, #21-01 Connexis(South Tower), Singapore 138632

In recent years, a number of sleep enhancing productsor systems have been developed. They can be categorizedinto three different groups. The first group deals with sleeptracking and provides recommendations for improving sleep.An example of such a product in this group is Sleep Tracker,which was developed by Zeo (Boston, 2003). This applica-tion helps to track users’ sleep cycles, providing them withinformation on their sleep patterns, and recommendationson how to improve their sleep quality. The second groupprovides assistance in waking up users in the appropriatestage of their sleep. Example products are Wakemate (PerfectThird Inc. San Francisco), Lark(Lark Technologies, CA)and Renew Sleepclock (Gear4, Hong Kong). These productstrack the users’ sleep patterns and wake them up gently byusing either sounds or vibrations from a wristband when theusers are in light sleep stage. The third group consists ofsleep induction systems, an example of which is Nightwave(Coherence Resources Inc., Portland). These systems help toinduce sleep through the playback of audio, white noise orsounds that match the frequency of the brainwaves to calmthe user down and help him fall asleep.

Existing sleep enhancement or regulation system usuallyrely on an open loop approach. In this research, we de-veloped a novel closed-loop system to help people gainfaster and better sleep. The EEG- and audio-based sleepsensing and enhancing system, called iSleep (interactiveSleep enhancement apparatus), collects EEG data to monitorsleep status and consequently provides user the appropriateaudio stimulation to shorten the time to sleep onset. We alsoconduct validation experiments to quantitatively assess theefficacy of the system.

II. METHOD

A. The iSleep Prototype System

Figure 1 shows the architecture of the iSleep prototype wedevelop. The system comprises of two major parts: iSleepmask to be worn by user and iSleep Mobile App to beinstalled in a mobile device.

1. Sleep MaskThe prototype of iSleep mask is shown in 2. The single

channel EEG unit based on Neurosky’s TGAM model isintegrated into the sleep mask that can be worn comfort-ably. The sensing electrode is silver-chloride metal electrodepositioned at FP1 while both reference and ground electrodesare attached to the left earlobe using a spring-loaded earclip.Besides EEG hardware, Bluetooth stereo speakers are alsoembedded into the iSleep mask at appropriate locations asshown in Figure 2. EEG signals are sampled at 512Hz and

978-1-4244-9270-1/15/$31.00 ©2015 IEEE 8050

Author's personal copy

Biological Psychology 95 (2014) 126– 134

Contents lists available at ScienceDirect

Biological Psychology

jo ur n al hom epa ge: www.elsev ier .com/ locate /b iopsycho

Enhancing sleep quality and memory in insomnia using instrumentalsensorimotor rhythm conditioning

Manuel Schabusa,b,∗, Dominik P.J. Heiba, Julia Lechingera, Hermann Griessenbergera,Wolfgang Klimeschb, Annedore Pawlizkia,c, Alexander B. Kunzd, Barry M. Stermane,f,Kerstin Hoedlmosera,b

a Laboratory for Sleep, Cognition and Consciousness Research, Department of Psychology, University of Salzburg, Austriab Center for Neurocognitive Research, University of Salzburg, Austriac General & Experimental Psychology, Ludwig-Maximilians University of Munich, Germanyd Department of Neurology, Paracelsus Medical University Salzburg, Austriae Department of Neurobiology, UCLA School of Medicine, USAf Department of Biobehavioral Psychiatry, UCLA School of Medicine, USA

a r t i c l e i n f o

Article history:Received 12 October 2012Accepted 20 February 2013Available online 30 March 2013

Keywords:InsomniaEEGHyperarousalNeurofeedbackMemoryConsolidation

a b s t r a c t

EEG recordings over the sensorimotor cortex show a prominent oscillatory pattern in a frequency rangebetween 12 and 15 Hz (sensorimotor rhythm, SMR) under quiet but alert wakefulness. This frequencyrange is also abundant during sleep, and overlaps with the sleep spindle frequency band. In the presentpilot study we tested whether instrumental conditioning of SMR during wakefulness can enhance sleepand cognitive performance in insomnia.

Twenty-four subjects with clinical symptoms of primary insomnia were tested in a counterbalancedwithin-subjects-design. Each patient participated in a SMR- as well as a sham-conditioning training block.Polysomnographic sleep recordings were scheduled before and after the training blocks.

Results indicate a significant increase of 12–15 Hz activity over the course of ten SMR training ses-sions. Concomitantly, the number of awakenings decreased and slow-wave sleep as well as subjectivesleep quality increased. Interestingly, SMR-training enhancement was also found to be associated withovernight memory consolidation and sleep spindle changes indicating a beneficial cognitive effect of theSMR training protocol for SMR “responders” (16 out of 24 participants). Although results are promising ithas to be concluded that current results are of a preliminary nature and await further proof before SMR-training can be promoted as a non-pharmacological approach for improving sleep quality and memoryperformance.

© 2013 Elsevier B.V. All rights reserved.

1. Introduction

Insomnia is characterized by a complaint of difficulty initi-ating sleep, maintaining sleep, and/or non-restorative sleep thatcauses clinically significant distress or impairment in social, occu-pational or other important areas of functioning (Littner et al., 2003;Riemann et al., 2010). From a psychological perspective insomniapatients typically complain of being unable to stop their reverber-ating thoughts and “rest their mind” which prevents them fromsleeping. Insomnia is considered a significant complaint and is

∗ Corresponding author at: University of Salzburg, Department of Psychology,Division of Physiological Psychology, Laboratory for Sleep, Cognition and Conscious-ness Research, Hellbrunnerstr. 34, 5020 Salzburg, Austria. Tel.: +43 662 8044 5113;fax: +43 662 8044 5126.

E-mail address: Manuel.Schabus@sbg.ac.at (M. Schabus).

associated with decreased quality of life, absenteeism, increasedwork and car accidents, as well as increased general health careutilization. Epidemiological research shows the high prevalenceof insomnia with about 30% of the general population complain-ing about some insomnia symptoms and 10% of the populationfulfilling criteria for an insomnia syndrome with classical symp-toms such as negative daytime consequences (Morin, LeBlanc,Daley, Gregoire, & Merette, 2006). According to DSM-IV criteriathe proportion of primary insomnia is estimated to be around3% (Gallup-Organization, 1995) to 6% (Ohayon, 2002). Empiricaldata demonstrate that insomnia is most often a chronic con-dition, defined as an inability to consistently sleep well for aperiod of at least 1 month. The consequences of chronic insom-nia are severe and include adverse effects such as deficits incognitive efficiency (Nissen et al., 2011), social discomfort and non-specific physical complaints (Gallup-Organization, 1995; Morin,Bootzin, et al., 2006; Stepanski et al., 1989). In addition to the high

0301-0511/$ – see front matter © 2013 Elsevier B.V. All rights reserved.http://dx.doi.org/10.1016/j.biopsycho.2013.02.020

ORIGINAL ARTICLE

Brainwave entrainment for better sleep and post-sleep state of youngelite soccer players ! A pilot study

VERA ABELN1, JENS KLEINERT2, HEIKO K. STRUDER1, & STEFAN SCHNEIDER1,3

1Institute of Movement and Neurosciences, German Sport University Cologne, Cologne, Germany, 2Department of Health and

Social Psychology, Institute of Psychology, German Sport University Cologne, Cologne, Germany, 3Faculty of Science, Health,

Education and Engineering, University of the Sunshine Coast, Maroochydore, Queensland, Australia

AbstractThe effect of sleep deprivation on psychophysical performance and well-being is comprehensively investigated. Researchinvestigating the effect of improved sleep is rare. Just as little exists about attempts to support athletic mental state andperformance by improving sleep quality. This study aims to investigate whether sleep quality of top athletes can beimproved by auditory brainwave entrainment and whether this leads to enhancements of post-sleep psychophysical states.In a pilot study, 15 young elite soccer players were stimulated for eight weeks during sleep with binaural beats around2!8 Hz. Once a week after wake-up, participants completed three different questionnaires: a sleep diary, an adjective list forpsychophysical and motivational state, and a self-assessment questionnaire for sleep and awakening quality. Fifteen sportstudents executed the same protocol sleeping on the same pillow, but without stimulation. Subjective ratings of sleep andawakening quality, sleepiness and motivational state were significantly improved only in the intervention group, but did notimpact their perceived physical state. In summary, eight weeks of auditory stimulation with binaural beats improvedperceived sleep quality and the post-sleep state of athletes, whereas the effect on physical level is assumed to occur in atime-delayed fashion. It seems to be worthwhile ! to further elaborate long-time effects and consequences on physical andmental performance.

Keywords: Neurostimulation, auditory stimulation, mental state, athletic performance, sleepiness

Introduction

Previous research has contributed to knowledge

about the importance and multidimensional influ-ence of sleep on human health, performance and

well-being (Harvey & Bruce, 2006). Noticeably,

most studies deal about the negative effects of sleepdeprivation. However, the whole range or potential

of sleep is still not entirely investigated. In particular,

in the field of high-performance sports, wherehealth, well-being and an optimal psychophysical

state is obligatory for maximal performance, the

benefit of sleep is not utterly examined and ways toimprove sleep are not exhaustively tested.

Research that attempts to improve sleep duration

or sleep quality is surprisingly rare, although theimpact and potential of sleep on both health and

performance are known. For instance, when a sleepextension of about an hour (from 7.5 to 8.5 hours)was added by Kamdar, Kaplan, Kezirian, and

Dement (2004), it revealed improved vigilance and

mood. Recently, Mah, Mah, Kezirian, and Dement

(2011) investigated the effect of sleep extension on

athletes’ performances. In this study, university

basketball players included five to seven weeks of

sleep extension (6!9 hours"2 hours), and they

found that the extended sleeping time leads to faster

performance in sprints, improved shooting accuracy,

decreased mean reaction time and sleepiness scores,

plus higher vigour and lower fatigue ratings. In

addition, athletes stated to have an overall better

physical and mental well-being during practices and

games.

Correspondence: V. Abeln, Institute of Movement and Neurosciences, German Sport University Cologne, Am Sportpark Mungersdorf 6,

50933 Cologne, Germany. E-mail: v.abeln@dshs-koeln.de

European Journal of Sport Science, 2014Vol. 14, No. 5, 393!402, http://dx.doi.org/10.1080/17461391.2013.819384

# 2013 European College of Sport Science

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Neuron

Article

Auditory Closed-Loop Stimulationof the Sleep Slow Oscillation Enhances MemoryHong-Viet V. Ngo,1,2,3 Thomas Martinetz,2 Jan Born,1,4,* and Matthias Molle1,41Institute of Medical Psychology and Behavioral Neurobiology, and Center for Integrative Neuroscience, University of Tubingen,72076 Tubingen, Germany2Institute for Neuro- and Bioinformatics3Graduate School for Computing in Medicine and Life Sciences4Department of NeuroendocrinologyUniversity of Lubeck, 23538 Lubeck, Germany*Correspondence: jan.born@uni-tuebingen.dehttp://dx.doi.org/10.1016/j.neuron.2013.03.006

SUMMARY

Brain rhythms regulate information processing indifferent states to enable learning and memoryformation. The <1 Hz sleep slow oscillation hallmarksslow-wave sleep and is critical to memory consolida-tion. Here we show in sleeping humans that auditorystimulation in phase with the ongoing rhythmicoccurrence of slow oscillation up states profoundlyenhances the slow oscillation rhythm, phase-coupled spindle activity, and, consequently, theconsolidation of declarative memory. Stimulationout of phasewith the ongoing slow oscillation rhythmremained ineffective. Closed-loop in-phase stimula-tion provides a straight-forward tool to enhancesleep rhythms and their functional efficacy.

INTRODUCTION

Brain activity oscillates at different frequencies, reflecting syn-chronized activity that organizes information processing andcommunication in neuronal cortical networks in a state-depen-dent manner (Buzsaki and Draguhn, 2004; Varela et al., 2001).The <1 Hz slow oscillation (SO) represents the most distinct ofthese oscillations that hallmark the electroencephalogram(EEG) during slow-wave sleep (SWS) (Steriade, 2006; Timofeev,2011). The SO is generated in cortical and thalamic networks andreflects global synchronous neural activity alternating betweenup states of membrane depolarization and increased excitabilityand down states of hyperpolarization and widespread neuronalquiescence, which spreads across the neocortex, also capturingsubcortical structures like the hippocampus (Isomura et al.,2006; Massimini et al., 2004). Importantly, the SO critically con-tributes to information processing during sleep: apart from aninvolvement in synaptic downscaling and homeostasis (Tononiand Cirelli, 2006), SOs play a causal role for the consolidationof memory (Chauvette et al., 2012; Diekelmann and Born,2010; Marshall et al., 2006). For this consolidating function, thesynchronization of fast-spindle activity (12–15 Hz) together withhippocampal ripples to the depolarizing up state appears to becritical (Molle et al., 2011; Molle and Born, 2011).

The obvious functional importance has stimulated attempts toinduce synchronized cortical SO activity through external stimu-lation, mainly by rhythmic electrical, transmagnetic, and auditorystimulation in humans and rats (Marshall et al., 2006; Massiminiet al., 2007; Tononi et al., 2010; Vyazovskiy et al., 2009). Impor-tantly, such studies imposed rhythms on the brain disregardingthe phase of ongoing endogenous oscillating activity, whichmight explain the overall limited functional enhancement inmemory retention accompanying SO induction. Here, we utilizedthe ongoing oscillatory EEG activity to apply, in a closed-loopfeedback system, auditory stimulation in synchrony with thebrain’s own rhythm, thereby enhancing and extending trains ofSOs during sleep.

RESULTS

Auditory In-Phase Stimulation Induces SO Activityand Enhances Memory ConsolidationSubjects (n = 11) were tested on two experimental nights,balanced in order. In the Stimulation condition, upon onlinedetection of an SO negative half-wave peak during nonrapideye movement (non-REM) sleep, two auditory stimuli (50 ms,pink noise) were delivered such that they concurred in timewith the predicted up phases of the detected and the succeedingSOs (Figure 1A). The stimulation started with onset of consoli-dated non-REM sleep and was discontinued after 210 min.During the Sham condition, stimulation time points were markedbut no stimulation was applied. The detection routine wasresumed 2.5 s after presentation of the second auditory stimulus.Averaging the EEG time locked to the first auditory stimulus re-

vealed a clear increase in slow oscillatory activity, in comparisonwith the Sham condition (Figure 1B). Whereas in the Sham con-dition an individual SO cycle occurred, the two auditory stimuli inphase with the predicted SO up states formed a sequence ofthree succeeding SO cycles (in the following referred to as an‘‘SO train’’). This suggests a resonating response of the networkinduced by the in-phase stimulation. The decrease in SO ampli-tude across these trains might reflect that the second auditorystimulus did not always hit the optimal SO up state phase (dueto jitter in the SO rhythm) or some kind of network refractoriness.Spectral analysis performed on SWS epochs during the stim-

ulation period showed that in-phase stimulation increased power

Neuron 78, 545–553, May 8, 2013 ª2013 Elsevier Inc. 545

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State-of-the art analysis and storage brain data infrastructure. Unprecedented amount of quality brain data.

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THE SCIENCE BEHIND DREEM

Dreem is the result of decades of neurosciences and hundreds of publications of our neurosciences partners, on sleep and brain stimulations. All the features have been tested rigorously internally, on thousands of nights.

French Armed Forces Biomedical Research Institute

Pr. Stéphane Charpier, PhDBrain and Spine Institute of Paris

Pr. Stanislas Dehaene, PhD INSERM / CEA / Ecole Polytechnique

Pr. Alain Destexhe, PhD CNRS / UNIC / Human Brain Project

Pr. Jan Born, PhDTubingen University

Manchester University & University of Wisconsin.

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