Charles Ellicott Commentary Lamentations 2:19

"Arise, cry out in the night, at the beginning of the watches; Pour out thy heart like water before the face of the Lord: Lift up thy hands toward him for the life of thy young children, that faint for hunger at the head of every street." — Lamentations 2:19 (ASV)

In the beginning of the watches — that is, of each watch, so that the lamentation was continued throughout the night.

Lift up your hands. — The wall is still addressed in its character as a mourner, witnessing the children dying of hunger and lifting up her hands as in despairing supplication for them.