We could, of course, elaborate a list of more than five such Hindrances, as there are quite a variety of different mental distractions or disturbances.
One discourse lists forty-four qualities which a monk should ‘efface’ (M. sutta 8); another mentions sixteen qualities which make a monk difficult to admonish (M. sutta 15); and another quite similar list mentions the sixteen qualities which defile the mind (M. sutta 7; cf. A.I,299, etc.) The commonest set is the three roots of unskilful action: greed (lust), aversion and delusion. The most fundamental mental obstruction is ignorance, which the Buddha said is caused by the five Hindrances, which are in turn caused by the three kinds of misconduct through body, speech and mind (A.I,113f).
So why did the Buddha highlight these five in particular?
Well, in practical terms, five is a reasonably manageable number of concepts. When you are in the forest meditating and you don’t have a book, you can probably remember these five categories, maybe by looking at the fingers of your hand and going through the list. Also, this group of five encompasses most of the range of disturbances we may come across in spiritual practice, especially if we generalize them in terms of basic human tendencies or how we usually relate to experience.
Maybe we sometimes have to deal with different kinds of specific disturbances, but basically we can probably fit most of our experience of disturbances into these five Hindrances if we look at the energy dynamic of each of them: reaching out, pushing away, collapse, over-activation and vacillation. For example, if we are disturbed by envy or jealousy, we can assess its energy dynamic (a kind of pushing away) to find an associated hindrance (ill-will) and gain some understanding of how to work with it.
Similarly if the disturbances are of a general nature, distractedness, discouragement, etc., and there is no obvious cause (distracted by sensual desires, discouraged because we lost our temper), we can access their energy dynamic and may find it helpful to apply some of the skilful means of the closest equivalent hindrance.
Of course, each specific mental obstruction and each particular nuance of a hindrance will need to be worked on with its own unique means. However, when we have experience of working skilfully with the coarser Hindrances, it is possible to apply this wisdom to help with working on subtler aspects of mind.
This reflection by Ajahn Thiradhammo is from the book, Working with the Five Hindrances, (pdf) pp.20-21.