The present invention relates to piperidine sulphonamide derivatives of formula wherein Ar1, Ar2, R1, R2, m and n are as defined in the description and claims, or pharmaceutically suitable acid addition salts thereof. The compounds of formula I are orexin receptor antagonists and the related compounds can be useful in the treatment of sleep apnea, narcolepsy, insomnia, parasomnia, jet lag syndrome, circadian rhythms disorder or sleep disorders associated with neurological diseases.