Optimal performance of wave energy converters requires appropriate control strategies. This is especially true of wave energy point absorbers, which are relatively small oscillators excited by waves. The two control methods for point absorbers which are most studied in the literature are reactive control and latching, which have major deficiencies. This article outlines a time-domain control method based on Model Predictive Control, which can be applied to any wave energy point absorber whose behaviour can be described by a linear state-space model. The control method is applied here to a semi-immersed vertical cylinder in deep water, excited by regular or irregular waves and oscillating in heave only; the motion may be either free or subject to amplitude constraints. Preliminary results from numerical simulations are presented and discussed. This control approach aims to obviate some of the limitations of already existing control strategies and to pave the way towards better control methods for point absorbers.