Efficacy and mechanisms of repeated closed-loop auditory exposure during slow-wave sleep for internet gaming disorder

Abstract

Internet Gaming Disorder (IGD) is marked by impaired psychological and social functioning but remains without effective treatments. Cue exposure therapy (CET) is typically administered during wakefulness to help extinguish addictive memories. However, recent studies suggest that sleep may be an optimal state for memory modulation. This study aimed to assess the efficacy of repeated closed-loop exposure to game sounds during UP-state of slow-wave sleep (SWS) on IGD. 84 participants meeting DSM-5 criteria for IGD were randomly assigned to sleep intervention/control groups (SIG/SCG) or awake intervention/control groups (AIG/ACG) with two consecutive days of intervention. During SWS of two intervention nights, around 300 sounds were exposed at slow-wave UP-state. While the awake groups received similar auditory cue exposure during the awake state for two consecutive days. Cravings, playtime, and P300 amplitude in the cue reactivity task were recorded at baseline, post-intervention, and follow-up intervals (1, 2, 3, weeks, and 1 month). Results showed that the SIG significantly reduced cravings (p < 0.001), and playtime (p = 0.009) at post-intervention and follow-up, whereas awake CET showed no effect. The SIG exhibited higher low-frequency and early spindle power, along with lower late spindle power after sound exposure. Notably, the linear increase in sound-elicited late spindle power across the 20 intervention blocks over two experiment nights was positively correlated with reduced cravings post-intervention (r = 0.54, p = 0.015), especially among participants achieving a craving reduction greater than 30% after one month. Our findings suggest that closed-loop auditory exposure during SWS presents a promising, non-invasive intervention strategy for treating IGD, potentially exerting its effects by modulating late spindle power.

Fig. 1. CONSORT flow diagram and experimental design.

A CONSORT flow diagram. B Experimental design. a. Timeline of sleep groups: Participants were split into two groups (SIG and SCG) and spent two consecutive nights in the sleep laboratory. SIG participants were exposed to approximately 300 game-related sounds per night, while SCG participants heard around 300 non-game-related sounds. Online game craving questionnaires and cue reactivity tasks were administered before and after the intervention. b. Timeline for awake groups. Participants were divided into two groups (AIG and ACG), On day 1, they completed online game craving questionnaires, a cue reactivity task, and a 50-min cue-exposure intervention (approximately 300 game-related sounds for AIG and 300 non-game-related sounds for ACG). On day 2, the cue-exposure intervention was repeated. On day 3, participants took the cue reactivity task and completed the craving questionnaires again. All four groups then filled out the online game craving questionnaires at 1 (T2), 2 (T3), 3 weeks (T4), and at 1 month (T5) post-intervention follow-up. Participants returned to the laboratory for the cue reactivity task 1 month later. SIG, sleep intervention group; SCG, sleep control group; AIG, awake intervention group; ACG, awake control group.

Fig. 2. Group differences in cravings and playtime at pre- and post-intervention, and follow-up.

A VAS score changes in SIG and SCG at baseline, post-intervention, and at 1, 2, 3 weeks, and 1 month follow-up. B QGU-B score changes in SIG and SCG at baseline, post-intervention, and at 1, 2, 3 weeks, and 1 month follow-up. C P300 mean amplitude changes in SIG and SCG at baseline, post-intervention, and at 1 month follow-up. D Playtime changes in SIG and SCG at baseline, post-intervention, and at 1, 2, 3 weeks, and 1 month follow-up. E VAS score changes in AIG and ACG at baseline, post-intervention, and at 1, 2, 3 weeks, and 1 month follow-up. F QGU-B score changes in AIG and ACG at baseline, post-intervention, and at 1, 2, 3 weeks, and 1 month follow-up. G P300 mean amplitude changes in AIG and ACG at baseline, post-intervention, and at 1-month follow-up. H Playtime changes for AIG and ACG at baseline, and at 1, 2, 3 weeks, and 1 month follow-up. *: p < 0.05; **: p < 0.01. All bar graphs display mean (±SEM). SIG, sleep intervention group; SCG, sleep control group; AIG, awake intervention group; ACG, awake control group.

Fig. 3. Time-frequency difference and its correlation with cravings.

A Top panel: TFR of responses to game-related cues versus non-game cues over two nights. Bottom panel: topographical plots showing game-related cue-elicited low-frequency power, early spindle power, and late spindle power. B Mean (±SEM) low-frequency power for both SIG and SCG across all subjects. C Mean (±SEM) early spindle power for both SIG and SCG across all subjects. D Mean (±SEM) late spindle power for both the SIG and the SCG across all subjects. E Correlations between power in the three frequency clusters and changes in VAS scores at T1, T2, T3, T4, and T5. F Correlations between power in the three frequency clusters and changes in QGU-B scores at T1, T2, T3, T4, and T5. G Correlations between power in the three frequency clusters and baseline playtime, along with changes in playtime at T2, T3, T4, and T5. H Correlations between power in the three frequency clusters and baseline p300 amplitude, along with changes in p300 amplitude at T0, T1, and T5. *: p < 0.05, **: p < 0.01, ***: p < 0.001. SIG, sleep intervention group; SCG, sleep control group; AIG, awake intervention group; ACG, awake control group.

Fig. 4. Fitting curve of power in three frequency clusters across intervention blocks and its correlation with therapeutic effects.

A A quadratic trajectory of low-frequency power across 20 intervention blocks in the SIG. B A quadratic trend for early spindle power across 20 intervention blocks in the SIG. C A significant linear trend for late spindle power across 20 intervention blocks in the SIG. D The slope of the linear trend for late spindle power across 20 intervention blocks positively correlates with changes in VAS scores in the SIG at T1. E The slope of the linear trend for late spindle power across 20 intervention blocks positively correlates with changes in GQU-B scores in the SIG at T1. F The y-intercept of the linear trend for late spindle power across 20 intervention blocks positively correlates with changes in VAS scores in the SIG at T4. G Mean (±SEM) VAS scores for the better and weaker groups at baseline and after one month. H Mean (±SEM) QGU-B scores for the better and weaker groups at baseline and after one month. I The linear trend of the late spindle power across 20 intervention blocks in the better and the weaker groups. ***: p < 0.001. SIG, sleep intervention group.