Pressures from the presidency are obvious in any term for any president. But for an older president, Reagan handled those pressures far better than most seniors.<quoted text>
Reagan had the tragedy of Alzheimer's later, maybe five years, difficult to determine exact date. A terrible disease. Pressure of the presidency may have been obvious in second term.
Obama was also exhibiting this kind of pressure during the first debate. Some probably even thought he had early Alzheimer's.
Second terms are usually never good for any president. Obama has only just begun.