Many people claim that their pets know, to the minute, when it's mealtime, walk time, or time for their owners to arrive home. So, the question remains: Can dogs tell time?

Research Speaks Volumes

It turns out that instead of measuring time in hours and minutes, dogs differentiate between long and short periods of time. In 2010, a group of Swedish researchers used hidden cameras to find out how dogs reacted when their owners left for different lengths of time. The research team wanted to know whether dogs behaved differently when left alone longer and whether they seemed to miss their owners more during longer separations. They worked with 12 dog owners that left their dogs at home alone for periods of 30 minutes, 2 hours, and 4 hours.

The dogs in the study became much more excited when their owners returned after 2 hours compared to 30 minutes. Researchers reported more tail wagging, attentive behavior, and overall energy from the dogs after longer periods of separation. This indicated that dogs knew that time had passed, and that they seemed to care. However, the researchers didn't observe a significant difference in the dogs' reaction to two-hour separations and four-hour separation.

Pattern Recognition

It seems pretty clear that dogs can tell that time is passing, but many pet owners are amazed by how well pets seem to learn household schedules. Can dogs tell time well enough to stick to a schedule?

Dogs, in particular, have evolved to be very skilled at picking up social clues and reading human behavior; it's part of how the earliest dogs found their place in human families. You may not realize that your body language sends subtle cues about your intentions, but your dog probably does. Maybe you always glance toward the door or stretch a certain way before your afternoon walk, or perhaps you stand up and walk toward the kitchen just a little more purposefully than usual when it's feeding time. If your dog is paying attention — and she probably is — she may be able to convince you that she's anticipating your every move in advance.

Most dogs are also quite good at figuring out associations between events, so your dog probably knows that when you pick up his leash, it's time for a walk, and that when she hears the car pull up outside, her people are about to walk in the door. Some experts have suggested that dogs may also form these kinds associations between daily events and changes in the environment. Your dog may know, for example, that when the sunlight coming through the window starts to dim, it's almost time for her dinner. Some researchers think that dogs may even be able use scent to tell how long you've been gone and when you'll potentially be back. When you leave the house in the morning, your scent lingers, but it fades throughout the day. Your dog may be able to figure out that you usually come home around the time your scent fades a certain amount, but scientists have yet to actually confirm this claim.

Fur-cadian Rhythms

Like most living things, dogs derive most of their time sense from their circadian rhythms. Earth takes approximately 24 hours to rotate once around its axis and experience a full cycle of night and day, so most life on the planet has evolved to wake, eat, survive, and sleep on that 24-hour schedule. Scientists have observed this in humans, dogs, cats, insects, fungi, and even some microbes.

Of course, every species has a slightly different circadian rhythm. Humans are naturally more active during daylight hours, for instance, while cats are naturally nocturnal. While humans tend to sleep through the night in six-to-nine-hour stretches (if we're lucky), dogs tend toward several shorter bursts of sleep a night.

An animal's circadian rhythm is governed by its genes, but these cycles are also very dependent on light and dark. They can also be influenced by changes in temperature or by social factors, like regularly scheduled mealtimes. Your dog's circadian rhythm probably plays a big role in when your dog thinks it's time to play, sleep, or eat. This internal clock may be what contributes to your dog's sense of time. Either way, we sure love spending time with our dogs!