I doubt it matters much to overall life expectancy, since the people effected most are the very elderly who will die soon anyway, if not from heat then from cat

I doubt it matters much to overall life expectancy, since the people effected most are the very elderly who will die soon anyway, if not from heat then from catching a sniffle or slipping in their shower. For young able bodied people to die from heat requires very extreme temperatures or a severe lapse in judgment.