Bhishma in Mahabharat explains, ‘The sinless, who observe Brahmcharya should not sleep during the day due to the sins that can arise from dream-state.’ These sins or undesirable qualities of dream state are explained: ‘In dream state, one faces defeat at the hands of Rajo Guna and Tamo Guna and having attained a different body he acts undesirably.’
Shastras explain that poisonous medicine, a metal plate, release of sperm, white clothing, dining at night-time, sleeping during the day and gossiping lead to the destruction of a Yati (ascetic).
Vyaas in Mahabharat’s Grihasta Dharmas adds that Grihastas should also refrain from sleeping during the day. They should not sleep during the first and final portions of night-time. Nor should they sleep during both Sandhyas. Similarly they should indulge in sexual activity with their wife only during the period of Rutu (sixteen days from the day of menstruation).
Narad explains, ‘To wander at night, sleep during the day, laziness, to slander, to intoxicate oneself and eating excessively or fasting excessively should be avoided.’ Anushasan Parva says, ‘Sleeping during the day causes a person to have a short and troublesome life with lack of prosperity and progress.’ Skanda Purana adds, ‘To sit upon a cow, to breath the smoke from a funeral pyre, to swim a large river, to absorb the rays of the sun whilst it is red in colour and to sleep during the day are all acts which should be avoided if one desires a fruitful life.’
Veidha Shastra explains the diseases caused by sleeping during the day: ‘By sleeping during the day, one can develop illnesses such as Pinas Roga (cold or flu) which can cause Kasa Roga (coughing) which can eventually lead to such diseases as Ksheya Roga (tuberculosis) which wears the body away.’ ‘By not performing physical exercise (Vyayaam), sleeping during the day and eating that which is prohibited, a person develops abdominal tape worms (Krami).’ Also, ‘Excessive sexual activity, eating things too salty, eating things too sour and eating things too acrid or hot all cause a persons blood to become diseased and their skin to whiten.’
Finally, they should never involve themselves in Gramya Varta (vulgar talk or gossip) - either by speaking such gossip or listening to such gossip. This again really applies to all. Shrimad Bhagwat says, ‘Those who choose to not listen to the pastimes of God, which is able to destroy sin and prefer to listen to vulgar talk destroy all their Punya and attain only the hells.’ Through such idle gossip one is wasted away and their lives amount to nothing. It wastes away their mind as it is filled with such filth causing confusion and unsteadiness.