Alterations in sleep EEG activity during the hypopnoea episodes.

The Obstructive Sleep Apnoea Hypopnoea Syndrome (OSAH) means 'cessation of breath' during the sleep hours and the sufferers often experience related changes in the electrical activity of the brain and heart. The aim of this paper is to investigate any possible changes in the human electroencephalographic (EEG) activity due to hypopnoea (mild case of cessation of breath) occurrences by applying the non-linear and linear time series methods. The results from this one-subject study indicated significant changes in the human EEG activity due to hypopnoea episodes by applying the non-linear, Lyapunov exponent method at C3 EEG electrode site. This non-linear method can be applied in future evaluation of sleep EEG transients during the OSAH episodes.