Lord, have mercy.
Do EOs normally pray to St. Michael the Archangel for protection?
But, for nighttime prayers, it's more common to say this prayer, blessing your bed with your cross (and sprinkling some holy water if you wish):
"Let God arise and let His enemies be scattered, and let them that hate Him flee from before His face! As smoke vanisheth, so let them vanish. As wax melteth before the fire, so let the demons perish from before the presence of them that love Christ, and who say with gladness, 'Rejoice, O most holy and precious Cross of the Lord, for thou drivest away the demons by the power of the Lord Jesus Christ Who was crucified upon thee, Who descended into hades and Who trampled on the power of the devil, and Who gave us thee, His precious, holy, and lifegiving Cross for the driving away of every adversary.' O most holy and lifegiving Cross of the Lord, help me together with the most holy Lady Theotokos and with all the saints, now and ever and unto the ages of ages. Amen."
(I'm going from memory here, so it may be a bit off.)