We have a Guardian Angel who watches over us who is assigned by God himself. We do not know their names for God does not want us to know so that we can call upon our Guardian Angel for help.
Here is a prayer that you can pray and ask your Guardian Angel when you need him and also pray at bed time.
Angel of God, My guardian dear, to whom God's love commits me here. Ever this day be at my side to rule and guide, Amen.
At bed time you can add this part also. My Guardian Angel, thank you for guarding me and keeping me safe from the snares of the devil and his evil doer's. Please guard me and guide me and protect me. With the Help of St. Michael the Archangel and Jesus Christ our Savior lock them in the pit of hell and seal the pit with locks and chains, in Jesus Name, Amen.
My Guardian Angel, thank you for guiding me and protecting me each day and helping me focus on our Lord Jesus Christ and stay in his heavenly graces. Please watch over me this night to get a peaceful nights rest. In Jesus name I pray, Amen.