by Reb Nati at Mystical Paths
The 49 days of of the Omer period correspond to the 49 gates of repentance. These in turn correspond to the 49 letters in the hebrew names of of the 12 tribes. It is though these letters and gates that we must make our return to G-D Almighty. The festival of Shavuot is the 50th gate.
This is the gateway of Hashem's "repentance",when Hashem Himself returns, as it were. That is to say, He returns to us in love. It is possible to reach all these gates and open them by reciting the psalms. If one is exceptionally careful to concentrate when reciting Psalms one can reach all 49 gates.
During the 49 days of counting the Omer we have to cleanse ourselves of impurity and return to Hashem. Then Hashem will return to us on Shavuot (Likutey Moharan II, 73). Thus we should immerse ourselves every day of the Omer in repentance. When we immerse in the Mikvah on Shavuot (predawn after learning all night) we are connected with the highest levels of Hashem's loving kindness and abundant mercy, and we can attain awesome levels of perception of Hashem. The illumination which radiates on Shavuot is supremely extreme. And this wisdom is itself an expression of Hashem's loving kindness and mercy.
Love is bound up with wisdom and perception, as is explained elsewhere. It is a wonderful thing to experience the holiness of Shavuot, and in particular the Mikvah of Shavuot - THE MIKVAH OF THE 50TH GATE - which becomes the wellspring of Holiness and purity for Israel (Likutey Moharan I, 56:7).
Now is a very good time to start to get up and recite Tikun Chatztot, as the time just changed nd we have only to say Tikun Leah (we don't say Tikun Rachael during this period) so it is much shorter. Let's make fresh commitment to rise and say this important prayer...
Rules of the tikun abbreviated: "Tikun rachel is only said on days when tachanun is recited. Tikun Leah is recited even on days when tachanun is not recited- Shabbos, Yom Tov including Chol HaMoed, Rosh codesh, the entire month of Nissan, Pesach Sheni, Lag B'Omer, from rosh chodesh Sivan until 7 days after Shavuot, 15 Av, from erev Yom Kippur until the end of the month of Tishri, Chanukah, Tu b'Shevat, Purim and Shushan Purim. Tisha b'Av only Tikun Rachel is said. Neither should be said after dawn (Ben Ish Chai, 9)
Together we can do it, if we just try we can live a life that is connected and fulfilling. Know for sure that you have nothing to lose but a little sleep, and much, maybe a special blessing, to gain.
BS"D - בסיעתא דשמיא