Investigation of Non-Painful Tactile Stimuli in Sleep: Amplitude and Frequency Analysis

Abstract

and Kales (R&K) had been used in the determination of sleep stages until 2007, the rules of the American Academy of Sleep Medicine are used today in determining sleep stages. 4 Sleep is not a steady state, rather it consists of constantly changing stages. One of these stages is the REM stage with rapid eye movements, BACKGROUND/AIMS: The aim of this study was to investigate evoked potentials elicited in the brain by non-painful tactile stimuli during sleep in amplitude-time and frequency-time domains. MATERIALS AND METHODS: Ten volunteers attended this study (mean age: 22.30±1.49 years). Non-painful, single type tactile stimuli were applied to the index and middle fingers of the volunteers’ right hand. During the night, the electroencephalography (EEG) of the subject was recorded via 40 channel EEG amplifier. The stages of the sleep were determined according to the standards of the American Academy of Sleep Medicine. Continuous wavelet transform was used for frequency analysis. The amplitude-time and the frequency-time findings relating to the periods of prior to sleep (PS), light sleep (LS), deep sleep, and REM were examined. RESULTS: While P50, N100, P200, N300, P900 and N_late components were observed both during the PS and the LS periods, the P350 and N450 were observed only in the PS, and the P450 and N550 components were observed only during the all-night sleep periods. CONCLUSION: In this study, it was also demonstrated by frequency-time analysis that there is a different information processing process during the PS and all-night sleep stages. In addition, with this study, we opened the way to show the dynamics of the non-painful somatosensory area associated with sleep stages.