noxious - injurious to physical or mental health; noxious chemical wastes; noxious ideas. harmful - causing or capable of causing harm; too much sun is harmful to the skin; harmful effects of smoking.
Newborn kittens, also sleep more -- upwards of 16 hours a day. Although newborns sleep a lot, it generally isn't continuous. Newborn kittens take frequent naps which often last for mere minutes at a time. Young cats usually develop their sleeping behaviors once they're around three months in age.
Your cat's age greatly affects his activity level. Young kittens, under 1 year old, tend to sleep more than adult cats while they are still growing. Newborn kittens actually sleep most of the day for their first few weeks of life. Senior cats, over 7 years old, slow down and sleep more than their younger counterparts.