Many people also meditate either before dinner or later in the evening. Others also meditate at noon. A short meditation at these times allows one to throw off some of the accumulated stress of the work-day and become rejuvenated for further activity. An important consideration is when your schedule will allow you to meditate. Having a time of the day set aside for meditation helps in maintaining regularity.
Different traditions give different answers.
Opening your eyes may be distracting. Experiment and see what works for you and then stick with your choice of technique. The most common physiological effects of meditation are reduced blood pressure, lower pulse rate, decreased metabolic rate and changes in the concentration of serum levels of various substances. When I meditate I experience physical pain in my body. The point of practicing meditation is to develop mindfulness.