Other safety precautions are that you should never massage a dog that is suffering from fever, shock or cancer. Also, as you massage, avoid any areas of unexplained swelling. Also, remember that massage is not a substitute for proper veterinary care, it is a compliment to it, and it has many benefits for their health.
Some studies have shown that your deep sleep should at least be 20% of your overall sleep. It means that since most adults need 8-9 hours of sleep, they will need about 1.6-1.8 hours of deep sleep to feel fully functional next day. However, the time of deep sleep is changed and that's mainly due to the change in the sleep need of different group of people. For instance: Age Group.
Light and Deep Sleep. During sleep, you alternate between cycles of REM (rapid eye movement) and NREM (non-rapid eye movement) that repeat about every 90 minutes. You spend about 75 percent of the night in NREM sleep, which consists of four stages of increasing relaxation. Stage one, or the phase between being awake and asleep, is considered light sleep. Deeper sleep begins in stage two, as your breathing and heart rate become regular and your body temperature drops.