Aron’s (often written Arons or Aron's) Depth Scale is a simple, widely used system for describing the depth or level of hypnotic trance. It was developed by Dr. Viktor G. Aron and popularized in clinical and stage hypnosis because it links observable signs and subject experience to numbered levels, making it easy for practitioners to communicate and choose appropriate interventions.
Key points of the scale
Purpose: Provide a practical, phenomenological way to classify how deep a person is in hypnosis, based on behavior, responsiveness, and subjective reports.
Structure: The scale typically ranges from light trance (higher numbers or lower numbers depending on version) to deep trance (opposite end). Many practitioners use a 1–10 or 0–10 format; the most common presentation uses numbers 1 through 10, where 1 is alert/very light trance and 10 is very deep (somnambulism).
Uses: Guides what suggestions or techniques are appropriate (e.g., progressive relaxation, symptom therapy, age regression, posthypnotic suggestion), helps monitor changes during a session, and communicates depth between practitioners.
Typical descriptions by level (common version, 1 = light → 10 = deepest)
1 — Light relaxation/alert hypnosis
Subject still fully aware, attention focused, minimal slowing.
Can follow instructions easily; critical faculty largely present.
Useful for suggestions for concentration, brief behavioral suggestions, and orientation.
2 — Relaxed attention
More physical relaxation and slowed breathing; some narrowing of attention.
Suggestibility begins to increase; simple suggestions work well.
3 — Moderate trance
Muscle relaxation, eyelid heaviness, altered time sense may start.
Simple motor and perceptual suggestions accepted (e.g., heaviness or lightness of an arm).
4 — Deeper moderate trance
Clear signs of hypnotic phenomena: automatisms, small amnesias, closed-eye catalepsy.
Good level for imagery, guided visualization, and symptom-focused suggestions.
5 — Light somnambulism / pronounced trance
Strong physical signs (muscle rigidity, catalepsy, sensory changes), possible partial amnesia for parts of session.
Suitable for many therapeutic interventions and experiential work.
6 — Somnambulism
Deeper amnesia, more dramatic hypnotic phenomena (anaesthesia, analgesia, negative hallucinations).
Good for age regression, deep therapeutic uncovering, and strong posthypnotic suggestions.
7 — Deep somnambulism
Very high suggestibility; complex phenomena like posthypnotic amnesia, age regression with good scene re-experiencing, and strong dissociative phenomena possible.
8 — Very deep somnambulism
Patient may show complete amnesia for suggested material, strong analgesia, and phenomena such as anesthesia of limbs.
9 — Near-complete dissociation
Minimal spontaneous movement, profoundly reduced awareness of surroundings; subject may require specific re-orienting suggestions.
10 — Deepest trance / somnambulism (sometimes called level 10)
Complete dissociation, unresponsiveness to normal external stimuli except direct hypnotic cues. Used rarely and only by experienced clinicians for very specific interventions (e.g., deep surgical analgesia in exceptional settings).
Observable signs commonly used to assign level
Eye signs: heaviness, fluttering, slow eye movements, partial opening with glazed gaze, closed eyes with slow blink reflexes.
Muscle tone: progressive relaxation, arm levitation or catalepsy, jaw slackness.
Respiration: slower, deeper breathing.
Responsiveness: degree and type of response to suggestions (motor, sensory, cognitive), reaction to external stimuli.
Memory and awareness: presence or absence of amnesia, time distortion, absorption in inner experience.
Clinical and practical considerations
The scale is phenomenological and helps practical decision-making; it is not a strict physiological measurement.
People vary: not everyone shows the same external signs at the same depth; some individuals are naturally deep responders or show signs earlier.
Safety: deeper levels require practitioner skill. Always monitor breathing, comfort, and be ready to reverse deep suggestions or bring the person to full alertness.
Flexibility: Many therapists use the level system to plan interventions but adapt based on individual responses rather than rigidly aiming for a number.
Ethical use: Always obtain informed consent for deep techniques (regression, age regression, amnesia) and ensure appropriate training before attempting them.
Brief example of application
If a client seeks help for smoking cessation, a therapist might induce trance to level 3–5 (moderate to light somnambulism) and give strong behavioral and posthypnotic suggestions. For acute pain control in dentistry, a trained clinician might aim for levels 6–8 to achieve reliable analgesia.
References and further reading
Aron, V. G. (original work is older and sometimes difficult to find in a single source). Many modern hypnosis textbooks and clinical manuals summarize the scale; look in standard clinical hypnosis texts (e.g., works by Milne, Spiegel, Yapko, and others) for related level descriptions and clinical guidance.