Chihuahuas sleep a lot, with the ability to snooze for up to 15-18 hours a day. This is normal for the breed and is not a cause for concern. They sleep so much because they have high energy levels and need time to rest and recover. Chihuahuas also enjoy sleeping with their owners and may sleep more when they are bored or lacking stimulation. However, a drastic change in sleeping patterns could indicate an illness, so it's important to monitor your Chihuahua's sleep habits.