In osteopathy is generally believed that the cranial bones are equipped with an inherent mobility, which like any other joint may face restrictions on movement and then somatic dysfunction. For this reason, different techniques are used with the aim of increasing the mobility of the cranial bones. Some of these have been effective in modifying physiological parameters related to the activity of the autonomic nervous system, such as cardiac function or sleep latency. This study aims to test the effectiveness of a specific craniosacral technique, compression of the fourth ventricle CV4, using the salivary marker alpha amylase, which is sensitive to changes in the activity of the autonomic nervous system. To patients recruited from students of AIMO, we will ask to provide saliva samples before and after CV4 treatment. In particular, saliva will be collected four times per patient: at the initial time, after administration of a stressful event (hand immersion in ice water), immediately after application of the CV4 technique and thirty minutes after the application of the CV4 technique. For each sample of saliva detected, we will proceed to measure the activity of alpha amylase and flow rate, variables sensitive to the activation of the autonomic nervous system.