The ancient scriptures describe the source of our consciousness as pure bliss.
The ancient scriptures describe the transcendental source of life as a field of pure bliss and happiness. The mind is always in search of happiness because essentially it is trying to get home. When the mind is directed outward it can never find this pure unconditional state of happiness, only ups and downs. But when we direct the mind inwards we can use this instinctive desire for happiness for it to be drawn towards the experience of transcending. That is why the natural effortless technique of TM works.
Although the subjective experience will differ from one meditation to the next, objective measurements show that there are consistent objective changes in the brain when the mind transcends, such as a significant increases of the “happiness hormone” serotonin and decreases of the stress hormones cortisol and plasma lactate. , 
We can objectively measure happiness and peace through changes in happiness and stress hormones
The more we repeat the experience of transcending, the more the decreases of the stress hormones and increases of happiness hormones will become permanent, also outside the meditation. This is one of the reasons for some spectacular improvements that one sees see after the long-term practice of TM.
Stress Hormones have a function in the body. When we are under attack we need them to be able to react quickly, in a so called fight-or-flight response, but we were never designed to be under chronic stress. Chronically high levels of stress hormones harm the nervous system and will eventually lead to illness. A direct connection is established between for example the level of cortisol and insulin resistance (diabetes 2) or obesity, or between the blood lactate level and high blood pressure.
Serotonin, on the other hand, regulates many of our brain functions. A low level of serotonin is now brought into connection with a series of problems, including depression, anxiety, migraine, anger, Alzheimer’s disease, sleep disorders, memory problems, compulsive acts, addictions etc. (Source WebMD). Medicines that regulate serotonin levels can temporarily ease the symptoms of these illnesses, but can not solve the real cause of the problem. Stress plays a major role in the reduced serotonin production in the brains.
The normal functioning of the human nervous system leads to health and happiness.
Essentially we can say that the normal functioning of the human nervous system leads to healthy and happy people. This is how we were designed to live, as that is our essential nature. Stress disturbs the normal functioning of the nervous system. Transcending is the opposite experience of stress, on one hand it is a state of deep inner peace and happiness, and this has a direct measurable effect on happiness and stress hormones, on the other hand it will activate the healing power of our bodies to remove the accumulated stresses, so that the body can again function normally again 24/7.
 JEVNING, R.; WILSON, A. F.; and DAVIDSON, J. M. Adrenocortical activity during meditation. Hormones and Behavior 10(1): 54–60, 1978. Reduction in Biochemical Index of Stress: Decreased Plasma Cortisol Levels.
 BUJATTI, M., and RIEDERER, P. Serotonin, noradrenaline, dopamine metabolites in Transcendental Meditation technique. Journal of Neural Transmission 39: 257–267,1976.