Ven. Yuttadhammo has written an interesting post about this topic on his weblog Truth Is Within. The post is called "Mahasi Sayadaw on Jhana".
Here is a quote from the section: "First Absorption and Conceit":
“Cunda, I will tell you about the cause of misconception and conceit in connection with the practice of meditation. Among my disciples, there are some monks who have attained the first absorption that is characterised by joy (pīti) and freedom from sensual desire, hindrances, and discursive thinking.”
Absorption (jhāna)² is the concentration of attention on one single object such as earth, water, in-and -out-breathing, an organ of the body or a corpse. This state of consciousness involving concentration and tranquillity is samatha jhāna. The other kind of absorption is vipassanā jhāna, which has as its object the contemplation and insight-knowledge of the three characteristics: impermanence, unsatisfactoriness, and insubstantiality.
Here is a quote from the section: "Abiding in Bliss Here and Now
The first absorption is not the practice of effacement that helps to root out the defilements. In the Sallekha Sutta, the Buddha calls it abiding in bliss here and now (ditthadhamma-sukhavihāra). While the meditator is in absorption, the mind is fixed on a single object. With the mind free from all unwholesome distractions, he or she is calm and peaceful. This state may continue for two or three hours.
The Buddha also pointed out how illusion and complacency may arise from the second absorption with its three characteristics — rapture, joy, and one-pointedness, or from the third absorption with its joy and one-pointedness, or from the fourth absorption with its equanimity and one-pointedness. Of course, the second, third, and fourth absorptions are more sublime than the preceding states of consciousness, but they ensure only bliss in the present life, and can by no means be equated with practice of effacement that is designed to eliminate defilements.
Nor can the practice of effacement be equated with the absorptions of unbounded space (ākāsānañcāyatana), unbounded consciousness (viññānañcāyatana), nothingness (ākiñcaññāyatana), and that of neither-perception-nor-non-perception (nevasaññā-nāsaññāyatana), which do not help to overcome defilements. They lead only to peaceful bliss and as such are called peaceful abidings (santavihāra).
Absorption in Insight Meditation
Insight meditation and absorption have some characteristics in common. When the practice of mindfulness is well established at the exploratory stage, i.e. knowledge by comprehension (sammasanañāna), there are initial application (vitakka), sustained application (vicāra), joy (pīti), bliss (sukha), and one-pointedness (ekagattā). Thus, whenever the meditator observes any phenomenon, his insight meditation is somewhat like the first absorption with its five characteristics.
When the meditator gains insight-knowledge of the arising and passing away of all phenomena, he is fully aware of an arising object without initial or sustained application. He has intense joy, bliss, and tranquillity, thus his meditation is somewhat like the second absorption with its three attributes.
The disappearance of the light, and so forth — the corruptions of insight (upakkilesa) — marks an advance in the insight-knowledge of the arising and passing away of phenomena. Then there is no joy, but bliss is very intense. The mind is tranquil and free from distractions. The meditator has the bliss and one-pointedness that are characteristics of the third absorption.
The higher levels of insight-knowledge such as knowledge of dissolution (bhangañāna), wherein the meditator sees only the passing away usually have nothing to do with joy. They are characterised by equanimity and one-pointedness. The former is especially pronounced at the stage of knowledge of equanimity about formations. At this stage the insight meditation is akin to the fourth absorption with its two attributes of equanimity and one-pointedness.
Furthermore, at times the meditator’s whole body disappears, giving him the impression of being in space. At that moment he is like a person absorbed in ākāsānañcāyatana jhāna. At other times, attention is fixed exclusively on consciousness and then the meditator’s state of consciousness resembles viññānañcāyatana jhāna. On occasions, it seems as though he were noting nothingness, a state somewhat like ākiñcaññāyatana jhāna. Sometimes the consciousness may be so transcendental that it becomes non-existent, a state on par with that of nevasaññā-nāsaññāyatana jhāna.
These characteristics that insight meditation has in common with absorption often leads to complacency, which is an obstacle to spiritual progress. In meditation it is necessary to note these unusual experiences and reject them. In the Sallekha Sutta, the Buddha, after pointing out the misleading nature of absorption, proceeds to spell out the practice of effacement that is calculated to root out defilements.
I do recommend reading the whole blogpost. Its well written and i think it will provide the answers you are looking for.