agrypnia

On certain Great Feasts (and, according to some traditions, every Sunday) a special All-Night Vigil (Agrypnia) will be celebrated from late at night on the eve of the feast until early the next morning.

In 843, with the end of Iconoclasm, the Feast of Orthodoxy was celebrated for the first time in the church of Blachernae with an Agrypnia ("holy Vigil"), which occurred on the first Sunday of Lent.

This rare disorder is characterized by severe insomnia, amounting to no less than complete lack of sleep (agrypnia) for weeks or months in a row, and associated with autonomic alterations consisting of profuse perspiration with characteristic skin miliaria (miliaria rubra, sweat rash or prickly heat), tachycardia, increased body temperature, and hypertension.