Tehillim

Can one say Tehillim by night?

Shalom!

Thank you for your question.

Is true that there is a view that one should avoid studying Scripture at night. This is based on the Kabbalistic teaching that words of Scripture (of which Tehillim is included) was specifically designated for the daytime while the Talmud and the Oral Torah was specifically designated for the nighttime. It is explained that according to Kabbala, Scripture represents "judgment" while the Oral Torah represents "kindness." Since nighttime also corresponds to “judgment” one should study Oral Torah ("kindness") at night in order to sweeten any harsh judgments. There is also a Midrashic teaching that when Moshe was on Mount Sinai for forty days he was able to distinguish between night and day by the subject matter that God would teach him. During the day God would teach him Scripture while at night He would teach him the Oral Torah. The Arizal was also particular to separate the study of Scripture and Oral Torah.

Le'halacha women can always say Tehilim and learn written scripture (Torah she'beksav) even at night time. the above Halacha applies to men and is as follows;

Tehilim may be recited as a form of prayer for someone who is sick or if one feels frightened, and in a case, where one would otherwise not learn, then it is permitted to either recite Tehilim or learn written Scripture (Torah she'bechsav). Same too when Scripture is studied at night along with the traditional commentaries, in which case the entire study has the status of "Oral Torah". Thursday night there is a leniency that one may recite the Shnayim Mikrah Ve'echad Targum. 

Tanchuma, Ki Tissa; Be’er Heitev 238:2; Ben Ish Chai, Pekudei 1:7; Kaf Hachaim, OC 237:9; Eishel Avraham, OC 238; Sha'ar Hatziun 238:1; Maharsham 1:158.