It is possible to measure these effects in a systematic way. The functioning of the artery can be measured by Peripheral Arterial Tonometry, (PAT) a simple monitoring device that measures blood flow using finger probes and a blood pressure cuff. Changes in the nervous system can be measured by using a 24-hour Holter monitor to record the heart rate. The 24-hour Holter monitor will also show if oxygen flow to the heart is decreased, as would happen during stress, by recording a continuous electrocardiogram (ECG). Feelings about stress can be established by questionnaires.