Abstract
<title>Abstract</title> <p>Hypnosis is an effective intervention to alleviate stress-related symptoms. Recent evidence has shown that a single session of hypnotic safety suggestions, combined with a post-hypnotic cue that enables reactivation of the safety feeling in daily life (a “safety anchor”), reduces physiological markers of stress anticipation during the following week. We here extend these findings by examining whether the intervention produced sustained effects on subjective well-being, sleep quality, and heart rate assessed repeatedly throughout the day. In this randomized controlled trial, 80 participants were allocated to either a 30-minute hypnotic safety suggestion combined with a safety anchor or a control condition. During the week before and the week after the intervention, participants repeatedly reported their well-being (including mood, acute stress, worry, rumination, and anticipatory stress) and sleep using smartphone-based ecological momentary assessments, while heart rate was continuously monitored throughout the day and night using smartwatches. Linear mixed-effects models provided no compelling evidence that a single hypnotic safety suggestion coupled to a safety anchor produced lasting effects on daily well-being, sleep quality, or heart rate during the week following the intervention. However, compared with the control group, the hypnosis group showed a trend toward lower heart rate during the two hours preceding bedtime. Overall, these findings suggest that while a single session of hypnotic safety suggestions coupled to a safety anchor has limited effects on subjective well-being and sleep quality, it may exert subtle physiological effects during the evening period preceding sleep.</p>