| Δ0 | progressive muscle relaxation before sleep itself | progressive muscle relaxation before bed |
| Δ1 | other structured relaxation techniques used for sleep | deep breathing exercises, body scan meditation, guided imagery, autogenic training |
| Δ2 | other pre-sleep wind-down habits | reading before bed, taking a warm bath, gentle stretching, dimming the lights before sleep |
| Δ3 | general sleep hygiene practices | keeping a consistent wake time, avoiding caffeine in the evening, keeping the bedroom cool, limiting screens at night |
| Δ4 | general stress-reduction and wellness practices | yoga, journaling, mindfulness meditation apps, workplace mindfulness breaks |
| Δ5 | everyday health habits unrelated to relaxation or sleep | brushing teeth, eating vegetables, jogging, using sunscreen |