Readers familiar with Larry Niven's Warlock stories will know that mana, the energy behind wizardry, is finite and of a local nature. It can be depleted by the repeated and excessive use of potent spells, such as the Warlock's Wheel. When venerable wizards, old beyond memory but protected by anti-ageing spells of their own making, enter an area the mana of which is depleted by potent spells or other strong wizardry, it will result in them instantly losing hair and teeth (not to mention the shrinking of other quite essential body parts), as their protective spells lose all potency.
For a long time I thought that Larry Niven's view was unique. A meticulously slow triple rereading of Morreion has now revealed that the same phenomenon occurred at least once during the 21st Aeon, when Ildefonse's cabal ruled part of the Dying Earth. It's a small clue, perhaps a double slip of the pen only, but a clue none the less. Jack, perhaps extrinsically and unintentionally, seems to be of the opinion that repeated use of the Spell of Temporal Stasis may only temporarily age one's appearance, whereas drunken wizardly quarrels are more serious and have an irreversible ageing effect on a wizard's appearance. There is, I admit, also another theory possible, but to a true Vancean, that hypothesis is simply unthinkable. Better stick to the facts, as given by the master of fantasy himself.