Dog Tired ? *
As we are all aware dogs like to sleep and often take many naps during the day : are they lazy or is there science behind your slumbering canine ? Those owners with Fitbits and the like will know that human sleep patterns are composed of two main types of sleep are rapid-eye-movement (REM) sleep and non-rapid-eye-movement (NREM) sleep.
Our bodies require sleep in order to maintain proper function and health. In fact, we are programmed to sleep each night as a means of restoring our bodies and minds. Two interacting systems—the internal biological clock and the sleep-wake homeostat—largely determine the timing of our transitions from wakefulness to sleep and vice versa. These two factors also explain why, under normal conditions, we typically stay awake during the day and sleep at night. Scientists have since found that the brain goes through characteristic patterns of activity throughout each period of sleep, and that it is sometimes more active when we're asleep than when we're awake.
When people are awakened from REM sleep, they often report that they had been dreaming, often extremely vivid and sometimes bizarre dreams. In contrast, people report dreaming far less frequently when awakened from NREM sleep. Interestingly, during REM sleep muscles in the arms and legs are temporarily paralyzed. This is thought to be a neurological barrier that prevents us from "acting out" our dreams.
So what of dogs and sleep? Dogs sleep patterns are different to their owners in that dog take many naps during the day and often require more than 14 hours of sleep per day. The amount of sleep varies according to the personality, breed and age of the dog. Senior dogs will sleep more and there are certain breeds that spend more time slumbering. Small dogs tend to sleep more, however even larger breeds such as the mastiff or the Newfoundland sleep more than 14 hours per day.
Age: puppies and older dogs both spend more time asleep than dogs that are in middle age. To support their growth, puppies may spend up to 20 hours asleep. Senior dogs naturally have a lower energy level and get exhausted more easily, requiring more sleep on a daily basis.
Breed and Size: though not universally true, bigger dogs will sleep for more hours per day than smaller dogs. Larger breeds of dogs tend to need more sleep and can sometimes sleep up to 18 hours a day even in middle age.
Activity: it may seem counterintuitive, but dogs that are very active, especially working dogs, usually need less sleep than dogs that are less active and are sedentary for most of the day.
The dog sleep patterns are similar to the human sleep patterns.
The first phase is known as the non rapid eye movement (NREM) phase and is has 3 stages. The 3 stages of the NREM phase are N1, N2, and N3.
N1 is the first stage of NREM and is a transition to unconsciousness; the dog loses control over his muscles but you may notice some movement in the limbs.
N2 is a stage where there is some brain activity involved, but the dog is very calm during the N2 stage. N2 is the lengthiest sleep stage, lasting for up to 45% of the total sleeping time.
N3 is also known as the slow wave stage. During the slow wave the dog has a decreased heart rate, lower blood pressure, decreased body temperature and breathes slowly. During this phase, the dog sleeps deeply and he does not react to noises or other disruptions even if they are loud.
The slow wave phase lasts for 10 to 15 minutes and is followed by the rapid eye movement phase (REM). This is an active phase and the dog seems more agitated during the sleep. You may notice his eyes rolling and the dog may even whine or bark and move his limbs. There is brain activity during the REM phase . The REM phase lasts for 10 to 15% of the total sleeping time. Puppies will spend more time in the REM phase.
As with people, the primary sleeping positions for dogs can be identified by which part of the body they are lying on. Each of these positions can have small modifications and can tell you about your dog’s mood and comfort.
Curled up : really resting ?
If you dog is sleeping on its back with all four paws in the air, it usually indicates a level of comfort and security. In this position, your dog is at its most vulnerable, which means it wouldn’t fall asleep like that unless it felt safe and at home. Sleeping in this position can also mean that your dog wants to cool down since exposing the full belly to air helps with temperature regulation as the hair is thinnest around the abdomen. Similarly exposing the sweat glands on the paws held vertically will help to dissipate heat. Years ago we were woken in the night by our GSD “falling off “ the wall where she used to sleep on her back with legs supported by the hall wall.
If your dog is sleeping on its side with its legs outstretched, it also indicates that your pup is comfortable and tired out. This is a very relaxing position for your dog and can also help with cooling by allowing plenty of airflow around the belly.
If your dog is sleeping on its stomach, it may not be in a deep state of sleep. This is usually because the legs and other muscles are not able to relax sufficiently to allow your dog to slide into deep sleep. However, some dogs may be able to fully stretch out and really doze off in this position. In other cases, this may be a restful position but one that your dog can easily jump up from, allowing your dog to relax without entering a full sleep cycle. If the surface is tiles etc then this is also a good position to cool down
In general, regardless of which part of the body your dog is lying on, the more curled they are, the less likely that they are in deep sleep. This is because curling up can keep your dog’s muscles more prone and less relaxed. This isn’t a problem, it just means that your dog is probably waiting for another time to get the really restorative sleep that it needs. It may also just mean that your dog wants to retain warmth, which it can most easily accomplish by curling itself up.
The way your dog positions itself relative to you or to other dogs or animals can also be telling about how comfortable and calm your dog feels. Sleeping back-to-back is often a sign of affinity, so if your dog lies down with its back to you or to another pet in your home, it is usually an indication that it has a feeling of warmth and trust toward you or that pet.
“Sleep...perchance to dream” Hamlet.
We’ve all seen the twitching paws and heard the yips of sleeping dogs but does this mean they are dreaming ? Dreams are thought to occur during REM sleep and as stated already dogs have very small bouts of REM sleep perhaps not sufficient to “dream” as we would understand it but REM sleep and associated movements have been found to be very important in dog training and the retention of skills. Scientists have discovered that REM sleep has both short term and long term impacts on the dog’s capacity to retain learning. An hours nap after learning a new skill was shown to have positive effect on the dog’s retention of the new skill , better than dogs which had no sleep or only a short 10 minute doze( though even the 10 minute snoozing dogs had a greater but temporary retention than dogs that had no sleep after training ). Again anecdotally I have often seen young puppies exhausted after their first training experience and would often sleep for an hour or so afterwards. Rather than being tired perhaps they are internalising their new skills?
REM sleep disorders can occur in dogs and is a condition where the “paralysis” of REM sleep does not occur and can result in flailing of limbs, kicking violently, running , biting , chasing and loud vocalisations. This is not an epileptic seizure but a sleep disorder thought to be caused by the impairment of serotonin release .Therefore dietary and pharmacological interventions are often prescribed along with a more energetic exercise regime.
“Let sleeping dogs lie” Troilus and Criseyde.... Chaucer
There is truth in this 14th Century adage. Another consequence of the shorter sleep cycle for dogs is that they are generally more easily awoken. Dogs are more easily awoken during short-wave sleep, but even during deep sleep, it’s not uncommon for a dog to wake up at light sounds. This may be even more common in certain breeds that have historically been guard dogs or protectors.
Being woken suddenly from non REM sleep can result in a startled bite response from the dog and is one of the three main causes of dog bites to children (the others being approaching food and ignoring warnings). Thinking of the dog’s sleeping posture the curled up dog is not necessarily relaxed about its security and being woken up suddenly will cause the dog to react defensively. Instead children should always be taught how to safely wake up the dog by standing away from the vicinity of the dog and shouting its name .
Sleep pattern changes.
Changes in sleep patterns can occur as part of the natural aging process of the dog . However, sudden changes can be indicative of the health of the dog and might need to be investigated in order to rule out certain conditions. Canine cognitive disorder , a type of age related canine Alzheimer seen in elderly dogs, is diagnosed by behavioural changes including changes in sleep patterns and insomnia. It is important therefore that owners understand the “normal” sleep pattern for their dog
“Dog tired “: Bede’s Ecclesiastical History of the English People