Considering the very large distances, I suppose it would require very little in the way of manual intervention or energy. But I wonder how safe it will be unles

Considering the very large distances, I suppose it would require very little in the way of manual intervention or energy. But I wonder how safe it will be unless at least one or two crew members are left awake to attend to the rest in case of emergencies. That also leaves the question of what method to use for hibernation. Many mammals already do, but we may require a drastic change in our physiology or dive into genetic engineering (without knowing long-term effects, it could be dangerous) or discover some substance to inject into our blood or replace it altogether so we may lower our metabolism.