Читать книгу Dental Management of Sleep Disorders - Ronald Attanasio - Страница 27

The determination of the sleep stage is dependent on brain wave activity or the electroencephalography (EEG) that is recorded during a sleep study, typically at an attended level I laboratory‐based study or polysomnography (PSG), recorded with surface electrodes over the skull. This will distinguish NREM from REM as well as the sleep stage during NREM sleep. NREM and REM sleep occur in varying proportions during sleep, and they also alternate in a cyclical fashion (Figure 2.1).

The typical pattern in normal sleep is for the individual to progress from wakefulness to the NREM sleep state, followed by the REM sleep state, and then alternating between REM and NREM stages. Overall, a night of sleep comprises about 75–80% of NREM sleep and 20–25% of REM sleep. A disturbance or alteration in the distribution of the sleep staging is typically associated with one of the various sleep disorders.

Figure 2.1 Sleep EEG.