public void night() {

        // End of simulation
        endOfSimulation = true;

        for (int i = 0; i < grid.getWidth(); i++) {

            for (int j = 0; j < grid.getDepth(); j++) {

                if (getSubject(i, j) == null) {

                    continue;
                }

                if (getSubject(i, j).getState() instanceof Dead) {

                    grid.place(null, j, i);

                    continue;
                }

                // Someone is still infected
                if (getSubject(i, j).isInfected()) {

                    endOfSimulation = false;
                }

                // Incubation
                getSubject(i, j).incubate();
            }
        }
    }