New Delhi: We spend one third of our life sleeping. There must be a good reason why nature makes us sleep for this long. Large number of studies all over the world has shown the beneficial effects of good sleep. Sleep deprivation, on the other hand, results in impairment of judgement, depression, heart problems, obesity and drastic reduction in general well-being of an individual. In an extreme case, sleep deprivation has also resulted in death through heart failure. In fact, the first sign of sickness is fretful sleep. How lack of sleep produces ill health has remained a mystery. Now, slowly, scientific investigations are solving this puzzle. One of the accepted theories so far has been that sleep helps in both consolidation and removal of memories. We perceive the world during the day through our senses and it results in memory formation both shallow and deep. Sleep, it seems, helps in consolidating and removing some of these memories uncluttering the brain. Another recent, but fascinating, theory (backed with experiments) has shown that sleep helps in flushing out toxic protein waste and biological debris from the brain, formed during waking hours. It seems that during sleep the relaxation of brain helps in opening up the channels through which the debris flows into the blood streams and is removed from it. Studies have also shown that sleep helps flush out harmful protein plaque (beta amyloid) which is responsible for neurodegenerative diseases like Alzheimer’s and dementia. Thus good sleep is extremely essential for a healthy brain and body. The build-up of toxins in the brain due to inadequate sleep also affects the body. Though there is very little understanding of how this happens, a probable cause is the passage of this information by the vagus nerve to different parts of the body. Scientific investigations have also shown that information of any slight change in the brain chemistry is transmitted to various organs by the vagus nerve, which plays an important part in keeping the brain and body in unison. As the brain starts getting affected by the debris build-up, the message via vagus nerve to various organs might be to slow them down, resulting in their lethargic action. Just like deep sleep, meditation also enables dissolution of memories. In fact, deep sleep and meditation have similar characteristics and it is quite possible that during meditation the flushing of toxins from the brain may also take place. A possible mechanism could be that since meditation results in the relaxation of brain, it may help in opening up the channels for flushing off the chemical debris. Memory is formed both by producing new neural pathways and certain chemical changes in the brain. Memory removal therefore is affected by changes in both these mechanisms. In deep meditation (where the focus is on a single thought for a long time, also called Sanyam) new neural pathways are formed and the old ones get dissolved. This dissolution may have a chemical signature thereby producing toxic debris which needs to be flushed out. How can we induce good sleep? Generally when the body is healthy and the person follows a good exercise regime, then this helps to produce deep sleep. Production of deep sleep can also be helped by meditation. Studies world over have shown that long term practice of meditation helps in toning both the mind and body. A good meditation practice to follow for quickly falling asleep is to close the eyes and focus attention onto the center of forehead. This can be done just before going to sleep and also when one wakes up at night and has difficulty in falling asleep again.