If a person wants that he should have sound sleep and should get sleepy instantly then he should recite it only three times

 اِنَّ اللہَ وَمَلٰٓئِکَتَہٗ یُصَلُّوْنَ عَلَی النَّبِیِّ یَاَیُّہَا الَّذِیْنَ اٰمَنُوْا صَلُّوْا عَلَیْہِ وَ سَلِّمُوْا تَسْلِیْمًا 

it is very tested and confirmed . just recite it and see the amazing benefit of it . it has been tested for many years in time of need and found to be very beneficial.

Muhammad Zeeshan Daska