The effects of breathing rate and pCO₂ levels on relaxation and anxiety in a non-clinical population

End-tidal pCO₂ levels were manipulated via presentation of two five minute meditation tapes differing in their instructions on rate of respiration (slow breathing = 10 breaths/minute, rapid breathing = 20 breaths/minute). The aim was to assess the effects of this manipulation on relaxation and anxiety in a non-clinical population under resting conditions and during a mild stressor (cold pressor test). Slowed respiration (and pCO₂augmentation) were associated with anxiety reduction and increased relaxation for both psychological and psychophysiological indices but this was not enough to counteract the effects of the cold pressor test. Implications for treatment of anxiety disorders are discussed.