The following quote comes from "Chapter Six: Daily Life" of Yuttadhammo Bhikkhu's book entitled "How To Meditate".
Basically, the five precepts are an absolute must at all times for seriously practising lay persons and monks. Without them, your spiritual progress and virtue would be strongly hindered and possibly also undone. In this case, complete abstention is required.
On the other hand, overeating, oversleeping, too much entertainment and too much sex (without misconduct) are not as critical as the five precepts, though they would be a hindrance nevertheless. In this case, only moderation is required for a lay person, not complete abstention.
In addition, observance of the eight precepts from time to time is also recommended. This is the usual observance for meditation retreats.
First, it is necessary to discuss activities that are harmful to one’s
mental clarity; activities one must avoid in order for the meditation
to bring about sustained positive results.
As I explained in the first chapter, “meditation” is the mental
equivalent to “medicine”. When taking medicine, there are certain
substances one must avoid; substances that will either nullify the
positive effects of the medicine or, worse, combine with the medicine
to create poison. Likewise, with meditation there are certain
activities that, due to their tendency to cloud the mind, have the
potential to nullify the effects of the meditation or, worse, pervert
one’s understanding of the meditation, causing one to cultivate
unwholesome mind states instead of wholesome ones.
Meditation is meant to cultivate clarity and understanding, free from
addiction, aversion, and delusion, and therefore free from suffering.
Since certain bodily and verbal acts are intrinsically tied to
negative qualities of mind, they are considered ‘contraindicative’ to
the meditation practice; they have an effect opposite to what is
desired, cultivating defilement instead of purity. Meditators who
insist on engaging in such behaviour will face great difficulty in
their practice, developing habits that are detrimental to both
meditation practice and personal well-being. To ensure the mind is
perfectly clear and capable of understanding reality, certain
behaviours must be taken out of one’s “diet”, so to speak.
First, there are five kinds of action from which one must refrain
completely, as they are inherently unwholesome:
One must refrain from killing living beings. In order to cultivate one’s own well-being, one must be dedicated to well-being as a
principle, refraining from killing any living being, even ants,
mosquitoes and other living beings.
One must refrain from theft. In order to find peace of mind, we must grant it to others as well; stealing is a denial of this basic
right to security. Further, if we wish to be free from addiction, we
must be able to control our desires to the extent of respecting the
possessions of others.
One must abstain from committing adultery or sexual misconduct. Romantic relationships that are emotionally or spiritually damaging to
others, due to existing commitments of the parties involved, are a
cause for stress and suffering and based on perversion of the mind.
One must refrain from telling lies. If one wishes to find truth, one must avoid falsehood; intentionally leading others away from the
truth is harmful both to oneself and others and incompatible with the
goals of meditation.
One must refrain from taking drugs or alcohol. Any substance that intoxicates the mind is obviously contraindicative to meditation
practice, as it is the antithesis of a natural, clear state of being.
Complete abstention from these activities is necessary if one wishes
for meditation practice to be successful, due to their inherently
unwholesome nature and the invariably negative effect they have on the
Further, there are certain activities that must be moderated or they
will interfere with meditation practice. These are activities that are
not necessarily unwholesome in and of themselves but will nonetheless
inhibit clarity of mind and lessen the benefit of the meditation
practice when undertaken in excess.
One such activity is eating; if one wishes to truly progress in the
meditation practice, one must be careful not to eat too much or too
little. If one is constantly obsessed with food, it can be a great
hindrance to progress in meditation since not only does it cloud the
mind, over-eating leads to drowsiness, both in the body and mind. One
should eat to stay alive rather than stay alive simply to eat. During
intensive meditation courses, meditators eat one main meal per day and
suffer no negative physical consequences as a result; whereas the
positive effects of such moderation are clarity of mind and freedom
from obsession over food.
Another activity that interferes with meditation practice is
entertainment – watching movies, listening to music, and so on. These
occupations are not inherently unwholesome but can easily create
states of addiction when undertaken in excess.
Addiction is a form of insobriety in a sense, since it involves
chemical processes in the brain that inhibit clear thought and clarity
of mind. Since the pleasure that comes from entertainment is momentary
and unsatisfying while the addiction and obsession carry over into
one’s life, a serious meditator should determine to make the best use
of their short time in this life by cultivating peace and contentment,
rather than wasting it on meaningless activities that don’t lead to
long term happiness and peace. If one wishes to find true happiness,
one must therefore moderate one’s engagement in entertainment.
Socializing on the Internet and similar activities should be
undertaken in moderation as well.
The third activity one must moderate is that of sleeping. Sleeping is
an addiction that is often overlooked; most people don’t realize how
attached they are to sleep as a means of escape from reality. Still
others become insomniac, obsessed with the thought that they are not
getting “enough” sleep, leading to increased stress levels and further
difficulty in falling asleep.
Through the meditation practice, one will find that one needs less
sleep than before since one’s mind will become calmer. Insomnia is not
a problem for meditators since they are able to meditate even in the
lying position and keep their minds free from stress. People who have
difficulty falling asleep should train themselves to watch the stomach
rise and fall, noting “rising”, “falling”, all night if necessary.
Even if they are not able to fall asleep (which is unlikely, given the
calm state of mind while meditating) they will find themselves as
rested as if they had slept soundly through the night.
Finally, it is worth mentioning that to truly gain results in the
meditation practice, a meditator should set aside at least a period of
time to remain entirely celibate, not just avoiding immoral sexual
activity, since all sexual activity is invariably intoxicating and
will be a hindrance towards attainment of mental clarity and peace.