Everyone sleeps -- animals included. Even insects! But although we have that in common with animals, the timing, duration, and quality of sleep varies depending on type, species, and many other factors. Generally, mammals sleep most similarly to humans, while birds, reptiles, and fish differ more significantly.
Generally, animals can manage their sleep well enough on their own, but many pet owners are curious about pet sleep habits. Read on to shed some light on what you can expect from animal sleep.
Mammal Sleep Patterns
Humans are mammals, so naturally, mammals have sleep patterns that are the closest to humans. And although mammals tend to experience light, deep, and REM sleep like humans, there's a wide range of sleep patterns among mammals. Some mammals, like puppies and kittens, may need up to 20 hours of sleep each day. (So do opossums and armadillos, who sleep about 18 hours a day. Compare that to horses and giraffes, who sleep less than three hours each day.
Though primates (including humans) typically concentrate our sleep to one long period (though sometimes, not quite long enough), sleeping multiple times throughout the day is more common for other mammals.
Bird Sleep Patterns
Compared to mammals, birds have remarkably flexible sleep. When migrating, birds can fly for months without stopping -- but they still need to sleep. When humans sleep, everything stops. But not birds.
Birds can actually sleep while flying, as one hemisphere of their brain sleeps while the other keeps them going. REM sleep in birds typically only lasts a few minutes. Some bird species may have limited sleep while migrating, then make up with much longer periods of sleep once they're on land.
Reptile Sleep Patterns
Reptiles may experience incredibly rapid sleep cycles compared to humans. Lizards experience a sleep cycle that lasts only about a minute and a half, while humans have a sleep cycle around an hour and a half. That means they go through hundreds of sleep cycles each night, while we only have a handful.
It can be difficult to tell when reptiles are sleeping. Though we humans close our eyes to sleep, reptiles like snakes do not. Instead they have transparent scales that protect their eyes -- but they're clear and we can't tell when they're closed. Typically, the best way to determine whether a reptile is asleep or not is if it's staying still.
Fish Sleep Patterns
Like reptiles, it can be difficult to determine when fish are sleeping. They may be mostly motionless and only occasionally move their tail fin to stay steady. Fish have adaptable sleep patterns, which often reflect the lighting and activity of their environment. Some fish have particularly interesting sleep cycles, like sharks, which require constant gill ventilation and have to stay swimming, even while they sleep. Sharks don't enter REM sleep or close their eyes.
Supporting Healthy Pet Sleep
Generally, maintaining good health for your pet will help them with healthy sleep. Feeding them a good diet and staying up to date on vet visits is key, as is giving them a healthy sleep environment and plenty of attention and activity during the day or other periods of activity. If you notice unusual changes in your pet's sleep patterns, talk to your vet to rule out any serious health concerns.