[header] How to wake up a cat [title] Recognize the sleep stage. [step] Normally, it's fine to wake a sleeping cat. However, there are two stages of sleep that are important to a cat's well-being: rapid eye movement (rem) sleep and non-rem (nrem) sleep, also called deep sleep. 
If a cat is deprived of these sleep stages, he may become irritable or lethargic. If you think your cat is in rem sleep or deep sleep, you may want to let him be.