  We show that by raising the lattice "adiabatically" as in all current optical
lattice experiments on bosons, even though the temperature may decrease
initially, it will eventually rise linearly with lattice height, taking the
system further away from quantum degeneracy. This increase is {\rm intrinsic}
and is caused by the {\em adiabatic compression} during the raising of red
detuned lattices. However, the origin of this heating, which is {\em entirely
different} from that in the bulk, also shows that one can {\em reverse} the
temperature rise to reach quantum degeneracy by {\em adiabatic expansion},
which can be achieved by using blue detuned lasers.
