Lifespan Integration vs Somatic Experiencing
A side-by-side comparison: mechanism, evidence, the conditions each treats, philosophical roots, and where they actually disagree clinically.
At a glance
Lifespan Integration
- Tradition
- Trauma-Focused
- Founder
- Peggy Pace (2003)
- Evidence
- Emerging evidence
- Focus
- Relational + Somatic + Integrative
- Format
- Individual
- Duration
- Medium-term (12-30 sessions typical)
Somatic Experiencing
- Tradition
- Somatic
- Founder
- Peter Levine (1997)
- Evidence
- RCT-supported
- Focus
- Somatic + Experiential
- Format
- Individual
- Duration
- Medium-term
How they work
Lifespan Integration
Core mechanism: Repeated chronological review of life memories allows the nervous system to integrate traumatic experience into the larger temporal context of a whole life, shifting implicit body-level beliefs about safety and self
Ontology: Fragmented temporal integration — the self is stuck in past time, experiencing old threat as present. The body has not updated its felt sense of when it is.
Somatic Experiencing
Core mechanism: Titrated pendulation between activation and resource states completes truncated survival responses trapped in the body
Ontology: Incomplete defensive responses (fight/flight/freeze) remain bound in the nervous system as undischarged survival energy
Conditions treated
1 shared · 3 Lifespan Integration-only · 5 Somatic Experiencing-only
Both treat
Only Lifespan Integration
Only Somatic Experiencing
What each assumes — and misses
Lifespan Integration
Philosophical roots: Siegel (interpersonal neurobiology — neural integration across time); van der Kolk (the body keeps the score — implicit memory); Schore (affect regulation and repair of early attachment); Bowlby (internal working models); Janet (dissociation as temporal fragmentation)
Blind spots: Limited controlled research base; mechanism of action not well understood neuroscientifically; can be over-applied to presentations that need more stabilization first; rapid pace of timeline repetitions may overwhelm some dissociative clients
Therapeutic voice: We're going to go through your timeline again. Just let the images come — you don't need to narrate or analyze them. Your body knows how to do this.
Somatic Experiencing
Philosophical roots: Reich/Lowen (body holds defense — Levine studied with both); Merleau-Ponty (lived body); Darwin (survival instincts); ethology (Tinbergen, Lorenz — animal defensive responses); James-Lange (emotion as bodily process)
Blind spots: Risk of over-physiologizing psychological meaning; limited manualization makes research difficult; can be vague in application
Therapeutic voice: Where in your body do you feel that right now? Just notice, without trying to change it.
Choosing between them
Lifespan Integration (Trauma-Focused) and Somatic Experiencing (Somatic) come from different traditions, which means they assume different things about what a person is, what causes suffering, and what the therapeutic relationship is for. The choice between them is often less about "which works better" and more about which set of assumptions fits the client and the therapist.
For deeper coverage: see the full Lifespan Integration and Somatic Experiencing pages, or use the interactive comparison tool to add more modalities to this comparison.