Saturday, February 17, 2007

Nidra

Nidra is exactly what I should be doing now, but alas, this is the only time I can steal away to update this fledgling blog. Nidra is considered the second "upastambha" or sub-pillar, of life. Like Ayurveda, modern science acknowledges the indispensability of sleep. However, it has not been able to specifically delineate the functions of sleep.

A modern anatomy and physiology text book defines sleep as "a state of altered consciousness or partial consciousness from which an individual can be aroused," (Tortora 2003). It goes on to discuss the two components of sleep, namely non-rapid eye movement sleep (NREM) and rapid eye movement sleep (REM). During NREM sleep, we move from light sleep to fairly deep sleep within the span of one hour. Body temperature and blood pressure decrease slightly. REM sleep is characterized by rapid eye movement and most dreaming occurs during this phase. NREM sleep and REM sleep occur cyclically, with REM sleep occurring every 90 minutes for a varying period of time. As we age, we experience shorter periods of REM sleep. For example, 50% of an infants sleep is REM sleep as opposed to 25% for adults. Brain activity and blood flow are higher during REM sleep, and it has thus been identified as an important factor in the growth and maturation of a child's brain. Adenosine is an important chemical in the physiology of sleep. Adenosine, liberated by ATP during periods of energy utilization, binds to receptors that inhibit the neurons responsible for waking us up. This is why we feel sleepy at the end of intense physical exercise and at the end of a long day. Sufficient amounts of adenosine bind to receptors, which interferes with our ability to stay awake.

Charaka has defined sleep as:

yadaa tu manasi klaante karmaatmaanah klamaanvitaah |
vishayebhyo nivartante tadaa svapati maanavah || ch.su. 21/25

When the mind and sense organs are exhausted, they no longer are able to perceive their objects. At this stage, sleep descends. Thus, wakefulness is dependent on the mind's association with the sense organs and in turn, their association with their objects. When we read a book, the mind interprets what the eyes are reading. When the mind begins to slow or wander, it can no longer analyze what is being read. At this stage, either sleep manifests or we get distracted with a different object that allures the senses.

Charaka has gone a step further than modern physiology textbooks to emphatically state that nidra is essential for the following reasons:

nidraayattam sukham duhkham pushti kaarshyam balaabalam |
vrshataa kliibataa jnaanam ajnaanam jiivitam na cha ||

Happiness, misery, nourishment, emaciation, strength, weakness, virility, sterility, knowledge, ignorance, life and death are all dependent on proper or improper sleep. With this in mind, he explains some rules (yes rules!! Ayurveda has many!) that govern sleep.

Raatri jaagarana (staying awake at night) and divaasvapna (napping during the day) are generally contraindicated. The former causes an increase of Vata dosha, which if prolonged, can result in emaciation, debility, and many Vata dominant disorders, such as psychological/neurological disturbances, as well as musculo-skeletal disorders. You are allowed to burn the midnight oil in one condition- that is as a remedy for napping too much during the day! Divaasvapna causes an increase in Kapha dosha, and as Vata and Kapha are opposites, wakefulness at night will mitigate the effects of napping during the day. The same is true for the opposite- if you stay up too late the night before, you may sleep 1/2 the amount of time you remained awake. However, you should sleep on an empty stomach. Often times we eat a heavy meal in order to induce sleep and sleep the day away. This is just going to aggravate the doshas even more. So best thing is to maintain a regular sleeping cycle, waking and sleeping at similar times everyday. If the regimen is breached, take immediate remedial measures to avoid further imbalance.

Divaasvapna is contraindicated at all times and for everyone. This is so because it leads to an immediate increase in Kapha dosha, as explained above. Increased Kapha manifests as physical and mental sluggishness and will in turn impair the functions of the digestive system and mind. Impairment of the digestive system is one of the causative factors in all disease processes, according to Ayurveda. Thus the "Agni," digestive fire, must be maintained in a healthy state at all cost. The exceptions to this rule include the summer season (especially Indian summers). During the summer, VAta dosha increases. Napping will mediate this relative increase. Similarly, Charaka explains that the elderly, children, and weak may nap, as well as those who indulge in excessive physical exercise/manual labor. Even those who are afflicted with grief, anger, fear, and intoxication have been given the ok. So it's ok to tell your slightly inebriated friend to "Sleep it off!" Thus the much loved siesta after lunch is not a very healthy option according to the classics. If its a 15-30 min. siesta that follows a meal, its ok. But beyond that is really pushing it! If you are accustomed to napping in the afternoon, don't immediately discontinue it. Wean yourself off gradually; otherwise you may experience withdrawal-like symptoms- headaches, irritability, etc.

Lastly, the types of sleep have been explained in Sutrasthana, namely-
1) Tamobhaava nidra: Sleep caused by excess Tamo dosha.
2) Shleshmasamudbhava nidra: Sleep caused by excess Kapha dosha.
3) Mana Shariira sambhava nidra: Sleep caused by excess mental or physical exertion.
4) Aagantuka nidra: Caused by poison, drugs, spirits, etc.
5) Vyadhi anuvartini: Due to a disease.
6) Ratrii svabhaava prabhaava nidra: Physiological sleep caused by the nature of night.

The only normal type of sleep is #6- Ratrii Svabhaava Prabhaava Nidra. The other types of sleep are abnormal and remedial measures should be taken in case they manifest often.