Changes

*Weather has an important influence on morbidity in the winter because cold, dry air leads to excessive dehydration of nasal passages and upper respiratory tract, and increased chance of microbial and viral infection. In general, total mortality is about 15% higher on an average winter day than on an average summer day, according to National Center for Health Statistics, 1978.

*Weather has an important influence on morbidity in the winter because cold, dry air leads to excessive dehydration of nasal passages and upper respiratory tract, and increased chance of microbial and viral infection. In general, total mortality is about 15% higher on an average winter day than on an average summer day, according to National Center for Health Statistics, 1978.

*Mortality rate during heat waves increases with age.<ref> Oechsli et al, 1970 </ref> <ref> Buechley et al, 1972 </ref> The elderly seem to suffer from impaired physiological responses and often are unable to increase their cardiac output sufficiently during extremely hot weather.<ref> Sprung C.L., 1979  </ref>

*Mortality rate during heat waves increases with age.<ref> Oechsli et al, 1970 </ref> <ref> Buechley et al, 1972 </ref> The elderly seem to suffer from impaired physiological responses and often are unable to increase their cardiac output sufficiently during extremely hot weather.<ref> Sprung C.L., 1979  </ref>

*It was noted that men who had taken bath in 15oC water for one-half hour over nine consecutive days before a trip to the Arctic showed less signs of cold-induced stress than non-treated men. It indicates that adaptation to cold temperatures can occur through repeated exposures. <ref> Radomski and Boutelier, 1982 </ref>

*It was noted that men who had taken bath in 15 degree Celcius water for one-half hour over nine consecutive days before a trip to the Arctic showed less signs of cold-induced stress than non-treated men. It indicates that adaptation to cold temperatures can occur through repeated exposures. <ref> Radomski MW, Boutelier C. Hormone response of normal and intermittent cold-preadapted humans to continuous cold. J Appl Physiol Respir Environ Exerc Physiol. 1982;53(3):610‐616. doi:10.1152/jappl.1982.53.3.610 </ref>

*To a great extent, the seasonal changes in the immune system are controlled by changes in the levels of various hormones, particularly melatonin. Serum levels of melatonin were found to be highest in the winter months in both normal individuals and SLE patients.<ref> Nelson et al., 2000 </ref> There is natural increase in ''bala'' (strength/immunity) of individuals during winter i.e. [[hemanta]] and [[shishira]] [[ritu]].

*To a great extent, the seasonal changes in the immune system are controlled by changes in the levels of various hormones, particularly melatonin. Serum levels of melatonin were found to be highest in the winter months in both normal individuals and SLE patients.<ref> Nelson et al., 2000 </ref> There is natural increase in ''bala'' (strength/immunity) of individuals during winter i.e. [[hemanta]] and [[shishira]] [[ritu]].

*Striking seasonal variations have been demonstrated in the plasma and saliva levels of the glucocorticoid, cortisol, which promotes carbohydrate metabolism. The lowest levels of cortisol were found in healthy individuals during spring and summer, while the highest levels were found during autumn and winter seasons.<ref>  Walker et al, 1997 </ref>

*Striking seasonal variations have been demonstrated in the plasma and saliva levels of the glucocorticoid, cortisol, which promotes carbohydrate metabolism. The lowest levels of cortisol were found in healthy individuals during spring and summer, while the highest levels were found during autumn and winter seasons.<ref>  Walker et al, 1997 </ref>