The benefits of praying Tahajjud:
From the authentic Hadith that praying tahajjud actually help safeguard you from illnesses and kind of sicknesses.
Out of the entire night, there is one part of the night which is more special and more valuable to pray tahajjud in and that is the last third of the night.
An authentic Hadith in which the prophet (saw) said that Allah subhanaw Taala descends to the lowest heaven in the last third of the night. Allah descends the last third of the night and then He looks upon the people of the earth and says who is calling upon Me for I am here to respond, who is asking Me for I will give, who is seeking My forgiveness I will forgive them, SubhanAllah.