This study investigated the effects of one session of "Yoga Nidra" (relaxation technique) on the breathing patterns/respiratory effort in the thoracic and abdominal chest regions of boys with disruptive behaviour using a Respiratory Inductive Plethysmography (RIP). The participants (n = 7) were aged 10-15 years and attending NSW, Department of Education (DET) special schools for children with disruptive behaviour (DB). Results were compared with three students (one female) aged 15 years without DB. The seven boys had previously participated in a 13-week yoga program. During this program participants were progressively taught the practice of "Yoga Nidra." The comparison group did not participate in the yoga program but underwent the same procedure for collection of data as the yoga group. Using Compumedics "ProFusion Polysomnography (PSG)" software and further analyses in "Polyman" European Data Format + (EDF), data were analysed by identifying breathing as unstable or stable. Unstable breathing was identified as fluctuations in rate/s of breathing effort, amplitude, cessation of breath, and thoracic or abdominal predominance. Results indicated that boys with disruptive behaviour generally displayed unstable breathing patterns throughout the pre-recording period and showed more stable breathing during "Yoga Nidra" compared with pre- or post-recording periods. There were also examples of reductions in thoracic dominance during "Yoga Nidra." The comparison group's breathing patterns throughout the three phases of the process were found to be stable.