P- Photophobia & Phonophobia - while experiencing a migraine attack, bright light and loud noise may produce sharp spikes in pain.
O- Ongoing duration of a severe attack - tension headaches normally last for three to four hours, and will usually clear up in under a day, often relieved by simple OTC medications, changes in position, and sleep.
U- Unilateral focus of the pain - normal headaches usually are experienced is a band of pressure across the top of the head, or radiating down into the face and neck.
N- Nausea and vomiting - people experiencing chronic migraine attacks may also feel other discomforts, such as nausea. In some cases, this can be so severe as to induce vomiting
D- Disabling intensity, which stops people from normal activity due to the intensity of the pain and discomfort.