Quick answer: Set can_sleep = false on bodies that need responsive collisions. Or apply a small impulse from area_entered to wake. Project Settings → Physics → 3D → Time Before Sleep tunes the global threshold.

A pile of crates settled. Player presses a button that triggers an Area3D explosion centered on the pile. Crates don’t move — sleeping bodies ignore the area trigger.

The Symptom

Settled physics objects don’t respond to forces, area effects, or fast moving bodies. Apply force returns; nothing moves. Calling apply_impulse explicitly does wake.

The Fix

extends Area3D

func _on_body_entered(body: Node) -> void:
    if body is RigidBody3D:
        body.apply_central_impulse(Vector3.UP * 5.0)   # wakes

Impulse wakes the body before applying force. Or globally:

# In Create
can_sleep = false

Body never sleeps. Slightly more CPU but responsive.

Global Sleep Threshold

Project Settings → Physics → 3D:
  Time Before Sleep:  0.5   # default 0.5; lower for sluggish sleep

Verifying

Drop crates, wait. Trigger area. Crates scatter. Without the fix, they sit. Print body.sleeping in _physics_process to confirm wake state.

“Wake explicitly. Or no-sleep on hero. Or shorter threshold.”

Related Issues

For thin collider tunneling, see tunneling. For Area3D detection, see Area3D.

Wake on intent. Bodies respond.