Don't use hot water, as this can destroy some of the milk's immunological components. (selfexpressions.com)
They will of course wake for hunger or thirst but they will also wake for pain relief, comfort, to get an increase in the immunological components in breastmilk, to help them cope with their developmental milestone and the changes in their brain due to this, if they are scared, cranky or bored! (themilkmeg.com)
Though no conclusive studies have been done to identify the immunological components of breast milk for children past 2 years of age, there's no reason to suppose they stop cold turkey once baby reaches a certain age. (romper.com)