HR people are often those who are asked to perform necessary evils in companies such as layoffs. When you are asked to harm your colleagues in order to promote the greater good, it may be highly stressful.
Companies can help by making it easier for the people who are about to be fired. Managers should also give HR personnel a break between the periods of layoffs. You should look after the emotions of colleagues whom you ask to take care of all the necessary evils.