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.
For most adults, 7 to 8 hours a night appears to be the best amount of sleep, although some people may need as few as 5 hours or as many as 10 hours of sleep each day. Women in the first 3 months of pregnancy often need several more hours of sleep than usual.