1. Health problems: If your dog keeps sleeping and refuses to eat, it may be because it is experiencing health problems. This may require you to take him to the veterinarian for a checkup. The veterinarian will conduct necessary examinations and diagnoses, and give appropriate treatment suggestions based on the condition.

2. Eating problems: If the dog keeps sleeping and refuses to eat, it may be because it is not interested in the food provided. Check your dog's diet to see if the appropriate food is being provided. If you've tried different foods and still can't whet your dog's appetite, it's recommended that you take your dog to the vet to determine if there's a medical problem.

3. Environmental issues: The dog’s environment may affect its appetite and sleep. If your dog is nervous or upset, he may be reluctant to eat or sleep. Take a look at your dog's environment and see if there's anything that can be improved, such as providing a comfortable sleeping area or increasing his activity level.

4. Age issues: Older dogs may sleep more and have less appetite. This is a normal aging process and you can provide it with the appropriate diet and rest according to its condition.

The symptoms of dog illness are as follows:

1. Vomiting: After the onset of symptoms, most sick dogs vomit. At the beginning of the disease, white gastric juice and stomach contents are vomited, and a very small number of them vomit. Vomiting dark red gastric juice with blood in the later stage.

2. Stool: Most sick dogs have yellow or gray-yellow loose stools in the early stage, and some have dark red or tomato juice-like loose stools.

3. Body temperature: generally rises to 39-41℃.

4. Appetite: After the disease occurs, the appetite of sick dogs is reduced or abolished. Most sick dogs have obvious thirst and vomiting after drinking too much cold water.