Our Sages describe the night as a time of justice and retribution. Under such circumstances the Zohar warns against falling before Hashem in Tachanun at night. Since the Divine attribute of judgment prevails, the results could prove spiritually dangerous.
At times a congregation’s Mincha will extend until after sunset, a time when it is questionable if it is night or day. Some halachic authorities recommend that during this time one should recite Tachanun without leaning down on one’s arm (Mishna Berura 131). This is the custom in Jerusalem and in other places outside of Israel (Responsa Teshuvos and Hanhagos 3,53).
At halachic midnight, the ascent towards dawn begins. During this time the strict judgment that prevailed earlier in the night starts to wane. Many authorities therefore permit falling down in Tachanun from midnight and onwards (Mishna Berura 131,18).
Text Copyright © 2010 by Rabbi Daniel Travis and Torah.org