**1. Introduction**

64 Sleep Disorders

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pinealocytes. *The Journal of Neuroscience*, Vol. 18, No. 6, pp. 2056-2062.

Metabotropic glutamate receptors negatively regulate melatonin sintesis in rat

Snoring and obstructive sleep apnoea (OSA) both exhibit multilevel upper airway obstruction. The Importance of evaluating the dynamics of the obstructing upper airway cannot be emphasised enough. Accurate assessment and evaluation of the upper airway could potentially lead to improved surgical and non-surgical treatment outcomes. Most of these patients would have undergone an ambulatory sleep study or a polysomnography prior to deciding what treatment modality is going to be offered to them. Treatment options available include nasal continuous positive airway pressure (nCPAP), mandibular advancement splints (MAS) or surgery. In terms of selecting a treatment option, in cases where the sleep study has confirmed moderate or severe OSA, nCPAP would be favoured. In the remainder and the nCPAP failed patients, further evaluation of the upper airway is useful and necessary. This chapter will not address sleep studies but will discuss various methods of assessing the upper airway and will include clinical evaluation of the upper airway during wakefulness and sleep.
