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.
In sleep, as in all things, cats are highly individual. Some cats sleep less than 16 hours a day and some sleep more; some spend as much as thirty or forty percent of their sleep time in a deep sleep cycle (this is particularly true of older cats).