The Buddha taught that there are five things called the five nivorns which serve as the biggest distractors to samathi, the enemy of charn, and the blocker of wisdom. If one of the nivorns come to possess our jit before our practice of samathi, that person will be distracted throughout the time, and find difficulty in finding peace.  Let me remind you what the five nivorns are:

1) Gammachanta
Thinking of nice images/form, pleasing sounds, stimulating smells, pleasurable taste and sexual/romantic relations.  Get away from your partner for a while for the practice of peace.

2) Emotions of dissatisfaction.
Wanting to remonstrate with this or that person.  Being angry or upset towards them.

3) Sleepiness.
Make sure that you are not too sleepy.  Don’t torture yourself, and make sure that you practice before you get too tired, or try the Buddha’s technique of pulling the ears, looking up, splashing water on the face etc.

4) Scattered emotion.
Thinking of this, thinking of that.

5) Having doubts or curious about the result of practice.  Having doubts about the teachings of the Buddha etc.
Having half of the motivation, which will not reap you the full result. It comes from the foolishness of oupatan.
Practicing sigln and having sigln in emotion 24/7 will get rid of the overloaded tension of nivorn beforehand.  However, before practicing apanusti gammatarn, which is the name for this type of samathi, there is always a teacher who will do what I will call the ‘distillation process’, where they will teach vipassana with the structure of the anusti (thinking), gammatarns to purify the soul as much as possible beforehand by dissecting illusion away from reality. This technique of seeing the way things are, seeing the way it lowers the effect of the distractions of gammachanta.  Once we grasp this concept in the jit, we say a compassionate prayer to jakamneiwein and ourselves, to cool down our spirit, and avoid distractions before we begin.
During the morning and evening ceremonies in the temples, the chanting activity always takes place before samathi.
The research of a scientist may give a very important answer as to why this particular pattern of chanting before meditation is actually very important, for the practice towards enlightenment.
A scientist called K. Kijsarun Chanpo, had tested the brain frequency with 60 volunteers by splitting 30 people to do chanting, and the rest, just meditation. He made them do 30 minutes of the dedicated activity, whilst taking notes of the brain activity all the time. The result showed that during the first 0-5 of the chanting group, the jit was still unstable.  However, 5-10, 10-15, 15-20, 20-25, 25-30 minutes into the practice, the brain wave showed that the jit had reached to the point of peace during and even after the practice. As for the meditation group, the study found that it is most effective during the 0-5 minutes of it.  However, once it entered 5-10, 10-15, 15-20, the brain was not still until the end.  This is because there was disturbance from nivorn 5 that had come to block the jit from doing samathi efficiently. Therefore, the jit that still has nivorn 5 will not have the ability to have samathi.  This means that the activities need to be practiced regularly to get rid of nivorn 5.

This test has been compared to the standard Alpha brain wave frequency when it was relaxed in the beginning of closed eyes period, which was the best period. In summary, this showed us that chanting before doing samathi is necessary, because the jit that has been focused on the chant has the effect of changing the Alpha brain wave, which can still be stabilized after five minutes, which is the time that you can enter samathi consistently. Chanting alone does not lead to nirvana, however it can be seen as a motivation factor for Buddhism practice and the purity of the soul. It helps in the focus, however other practices including the gammatarns and vipassana practices are the most crucial parts to enlightenment.