Chronic stress correlates with shorter telomeres, as well as with worse health. Via EurekAlert! researchers are proposing a mechanism by which telomere length is reduced by stress, leading to a worse immune response: "Short telomeres are linked to a range of human diseases, including HIV, osteoporosis, heart disease and aging. ... an enzyme [called telomerase] keeps immune cells young by preserving their telomere length and ability to continue dividing. ... the stress hormone cortisol suppresses immune cells' ability to activate their telomerase. This may explain why the cells of persons under chronic stress have shorter telomeres. ... When the body is under stress, it boosts production of cortisol to support a 'fight or flight' response. If the hormone remains elevated in the bloodstream for long periods of time, though, it wears down the immune system. We are testing therapeutic ways of enhancing telomerase levels to help the immune system ward off cortisol's effect. If we're successful, one day a pill may exist to strengthen the immune system's ability to weather chronic emotional stress."