Complex sentence: Existing literature provides consistent evidence that sensitivity to hot and cold surfaces declines with age and that there is also a gradual reduction in the effectiveness of the body in thermoregulation after the age of 60.
Split into simpler sentences: Existing literature provides consistent evidence that sensitivity to hot and cold surfaces declines with age. There is also some evidence of a gradual reduction in the effectiveness of the body in thermoregulation after the age of 60.