Why do stress and emotional factors trigger raynauds episodes?

Chemical transmitter: Emotional stress, such as anger or anxiety, causes the release of chemical transmitters (called hormones if they travel through the blood, called neurotransmitters if they travel down a nerve fiber) which can increase muscle tone (including the tiny muscle fibers around arteries) or increase the likelihood of muscle fiber contraction... Both of which may lead to vasospasm and raynaud's symptoms.

Trigger for Raynauds: Stress is the trigger for raynauds. It is also termed a vaso spastic disease.