The interplay between sleep and behaviour in dogs
Despite how important we know sleep is, we still don’t know very much about it in dogs.
One of the reasons for this is that sleep can be very hard and expensive to study properly. If only it was as simple watching your dog chasing rabbits in their sleep! There are many challenges of studying sleep states in the laboratory, not least because laboratories aren’t always conducive to going to sleep!
For animals, studying the brain can involve lots of training to teach them to stay still voluntarily in typically aversive situations. I don’t know about you, but I get fidgety when I know I have to stay still. Some of these methods can be very expensive and time-consuming.
In his book, neuroscientist Dr Gregory Burns explains how he trained dogs to undergo fMRI procedures. Because of the noise and equipment, this can be a lengthy and time-consuming procedure. His procedures were done with dogs who were awake. This removes one of the difficulties for scientists studying sleep in dogs: trying to capture sleep.
Other fMRI processes involve weighting the dog down. Dogs can also be trained to accept weighted blankets or restraints to hold them still so their brains can be scanned effectively.
In real life, if you have a dog who has suspected brain-related disorders, an fMRI head scan may be used. Usually, the animal is sedated in some way. However, sedation changes activity in the brain. That makes it hard to identify what happens in an ordinary dog brain that has not been influenced by sedatives.
Despite how amazing the information can be, because of its expense and complexity, this method is not used much with dogs. It is therefore difficult to know if the results can be interpreted as meaning all dogs are the same.
The polysomnogram
The one benefit of fMRI is that it gives you information from throughout the brain. It’s easy to see what’s going on in the deepest, most ancestral parts of the brain. This is where a lot of sleep-wake stuff happens. Because sleep is such an ancient process, it involves brain structures that are not always easy to study with other methods.
Another way to study the brain which is more simple is the EEG or electroencephalogram. The first EEG experiments were conducted on animals in 1875. It is a much more straightforward process than an fMRI and the equipment is much cheaper. Also, there is much less training involved.
An EEG measures the electrical activity in the brain. It does so with a network of monitors attached to the head – the kind of thing you probably think of from movies. The electrodes placed on the scalp detect neural activity.
One problem with them is that they don’t see very deep into the brain, where a lot of sleep activity actually occurs. It’s also not very good at pinpointing more precise things in the brain.
For that reason, a polysomnogram is a bit more complex. It may also involve taking heart rate and breathing rate measurements too. It can also involve measuring oxygen levels too.
This is often used in canine sleep and epilepsy studies because it can be used in natural settings, it’s less scary than an fMRI and it’s cheaper.
While it may not give detailed insights, it is more than capable of measuring different phases of sleep in dogs.
What polysomnographs can tell us about canine sleep
Studies involving polysomnographs can be much bigger than ones involving fMRI. The equipment is cheaper and it’s easier to use with different dogs.
They can tell us, for example, how quickly dogs fall asleep.
You’ll know yourself that sometimes it can be really tough to get to sleep. This is more likely after recent exercise or if you’re required to go to sleep at different times than usual. It can also be hard to get to sleep if you’ve had an emotional day. Unlike us, it’s much less usual a dog’s sleep will be challenged by caffeine or alcohol.
On the other hand, you’ll also know that sometimes, it’s really easy to drop off. A lot of the time, that is because of the build-up of adenosine which produces something called ‘sleep pressure’. If you’ve had a nodding head and long blinks during a late night television programme, you may have felt that sleep pressure. Other times, though, this can be as a result of exercise earlier in the day, or simply being awake for a long time.
A polysomnograph study can investigate how long it typically takes a dog to drop off after an event.
The dogs could have a positive emotional experience, like a fun game with their humans. They could also be subjected to negative emotional experiences, such as being left in unfamiliar environments or facing a threat.
The challenges of studying sleep after emotional events
As you can tell from that last description, there are huge ethical implications of deliberately subjecting dogs to unpleasant or aversive experiences. This affects all kinds of canine research in fear-based behaviour or in studying aggressive behaviour of other kinds. It also affects sleep studies if you want to understand the impact of emotional events on them.
This presents another challenge as well, because sleep is very species-specific. It’s also altered by age or lifestage. How dogs sleep is not the same as how humans sleep, and it’s not the same as how rodents sleep. Rodents and humans are most frequently studied when it comes to sleep quality.
Yet the composition of rodent sleep or human sleep is different from dog sleep.
Understanding how dog sleep differs
It is not easy to compare rodent sleep to dog sleep. This is also affected by the fact that many dogs adapt to human sleep patterns. Humans are diurnal, meaning we are awake during the day. Some scientists argue it’s more natural for humans to have one long sleep at night and a nap in the afternoon. Even so, on the whole, we are awake in the day.
However, other canid species are crepuscular, meaning they are most active at dawn and dusk. There is a lot of debate about whether dogs are crepuscular or not, and no doubt, some information comparing free-ranging dogs to captive wolves or even free-ranging wolves equipped with cameras will also help us understand whether dogs differ from wolves. Yet we also know that selective breeding means our dogs are perhaps not the same as free-ranging dogs, particularly where human habits have influenced canine habits.
Understanding sleep in dogs
One of the major gaps in our understanding is in simply understanding when dogs sleep and what is happening during that time.
For such an important event in a dog’s day, you’d think we’d have a better understanding of it!
What we then struggle to understand is the impact of good and bad stuff on sleep. In other words, if our dogs have a great day, does it change their sleeping patterns or their sleep quality?
And what about if they have a bad event?
Although we understand that emotional events affect sleep for rodents and humans, it is much less well understood in dogs.
Some studies have attempted to understand how sleep changes if our dogs have had a good day or a bad day. These are limited by the equipment, which can only record general things like whether the dog is in NREM sleep or in REM sleep, and if this is different for the individual dog compared to normal. It is also limited by the fact that nobody would argue with the ethics of giving a dog their best day ever and seeing how that affects their sleep, but there are huge ethical issues in subjecting a dog to an unpleasant experience of any intensity.
It’s also not particularly naturalistic. Should such things happen naturally to our dogs, we don’t have the equipment available to make a quick study of their brain during sleep after the event.
Why research might be useful about sleep and emotion in dogs
In humans, most major psychological or psychiatric conditions come with sleep disturbances. It can be hard to know if the condition is causing the sleep disturbance, or whether the sleep disturbance is contributing to the condition.
In many cases, it is probably bi-directional. One affects the other.
It is very similar, no doubt, for behavioural challenges with our dogs. Common sense tells us that if our dog has not slept well the night before, they may be more likely to bark and lunge at other dogs. It also tells us that they might be more likely to cope if they’ve had a good night’s sleep.
Understanding how life affects sleep would be of profound help for dog lovers.
It would be an easy way to understand how stressful events were impacting the dog.
Understanding sleep quality would be a useful measure of how kennelling was affecting dogs in boarding facilities, shelters or laboratories.
We could understand how dogs were coping with events like surrender or assistance activities. It could also be a useful measure of the difference in life quality between dogs taught with rewards and dogs taught with punishment and aversives. If we wanted to understand if our dogs enjoyed different activities, understanding their sleep afterwards could contribute to what we know about the dog’s experience.
It could also help us understand more about seizure disorders. Many seizures happen when dogs are asleep, for example, or during the night. Other disorders such as narcolepsy or sleep disturbance would also benefit from more research.
What existing research on sleep in dogs suggests
Dogs are polyphasic sleepers, unlike humans. This means they sleep in many phases. Some people take this to mean that dogs are restless sleepers or need different places to sleep. It’s not the case. It simply means they don’t just sleep from 10pm-6am like humans might.
Although dogs sleep more at night and mimic human sleep patterns, it’s hard to know that this is not a result of life with humans. There are no studies that compare the habits of free-ranging dogs with dogs in the home, for example, although it is likely that the next decade will see such research emerge.
Research on free-roaming dogs is very limited when it comes to sleep. Such studies have historically depended on human observation in real-life, rather than in videoing dogs. In free-ranging wolves, collar cameras can be used alongside GPS data from GPS trackers which could indicate when the wolves are at rest, but this does not mean that they are sleeping.
Indeed, dogs have states of wakefulness where it’s hard to tell if they are asleep or awake or some drowsy in-between state. It’s difficult, although not impossible, to get this data.
So far, most studies of canine sleep happen in the laboratory. Little is known about how this affects the onset, duration and quality of sleep. It usually involves the presence of a researcher, which may also affect our dogs. This is especially true where we are trying to study their emotions.
It can also be challenging to study canine sleep and emotion because what researchers decide is ‘aversive’ may not be to the dog, and what they decide is pleasant may not be, either.
Canine sleep and emotion
The studies on canine sleep and emotion are hard to interpret.
For example, they may set up a ‘positive’ situation involving play with the researcher. For some dogs, this will be lots of fun. My dog Amigo would have loved the opportunity to play with new humans. My dog Lidy, well that depends.
Even things like exposing dogs to potential threat are not always as easy to extrapolate meaning from. For example in some studies, captive foxes will work for the opportunity to engage in territorial behaviour. In other words, thinking a bit of barking behind the fence is experienced negatively to the animal may not be as clear-cut as all that.
They’re also hard to interpret because they are very small. Small datasets can produce dramatically different results just because of a handful of results.
They rarely take into account the age of the dog other than being ‘older than 1′. Yet adolescence and adulthood are different. They affect dogs’ needs and responses to situations.
When they take into account personality and individual differences, research on sleep in dogs can be flawed because reliable “temperament tests” in dogs do not really exist.
Canine behaviour is nuanced. It fluctuates depending on health, needs, situation and emotional state as well as age. REM sleep differs, for example, for adult individuals compared to adolescents. For this reason, replication in sleep studies for dogs is absolutely vital.
What remains unknown
Until we have more research that has been replicated and is more capable of nuance, there is a lot that remains unknown.
For example, there are very likely to be breed differences that will affect our dogs in the home. We already know that the quality of sleep in short-nosed breeds is, on average, poorer than that of other dogs. Our dogs’ bodies are likely to affect their sleep quality in ways that can be very challenging to rule out.
There will be undoubted complications from other factors like hormone or neurotransmitter levels. For example, oxytocin is sometimes reductively referred to as the ‘bonding’ or ‘love’ peptide. But is also implicated in ‘us’ vs ‘them’ aggression. It’s not as simple as all that. This affects the kind of events that a reseacher could set up as ‘positive’ experiences or ‘negative’ ones.
These things may not seem very important until we consider the impact of social relationships on sleep.
What is known about sleep in dogs and their emotions
Getting good quality sleep impacts our mood and our emotions. It affects our relationships and our behaviour. Simply because it’s hard to research doesn’t mean we don’t feel the impact of good sleep every single day.
No doubt these factors are true for dogs as well. If our dogs are struggling with maladaptive barking and lunging that interferes with healthy functioning, sleep may well be something we need to consider.
We could consider, for instance, if they struggle less after a good sleep period. Perhaps good sleep helps them cope better.
Or it could be the reverse. Maybe a lot of interrupted sleep actually means they dysregulate more easily than they would do normally. This means they can cope with less than they would do under other circumstances.
It may also be that if they are spending long periods of the day or night on edge that this interferes with their sleep. For example, one of my neighbours has a dog who sleeps on the back of the sofa near an open window. No matter what happens, the dog is awake and barking. It’s very unlikely they are getting enough restful sleep.
In summary
Sleep is important to our dogs. It is part of the big picture.
The best thing we can do is look at our dog’s entire life, including their health, their diet and their exercise. We can look at immediate triggers and consider management, just as we can look at the more general things that impact on their behaviour.
If our dog seems to struggle, considering their sleep levels is an important part of thinking about how we can help them cope better. This may be part of our work on resilience. Whenever we are trying to build our dog’s resilience, good sleep should always be a part of the programme. The Lighten Up Resilience Roadmap is a free e-book that you can download to help you do that. There is also a short webinar to help you implement these skills.