The first point to make is that some humans fall asleep as fast as cats and dogs. It is difficult to generalise. You could tackle the question from the other end and ask why do humans have difficulty getting off to sleep? There’s a long list of reasons and these reasons don’t apply to cats. This then provides one answer to the question.
For example, some people don’t get to sleep quickly because they are jetlagged, or suffer from delayed sleep phase disorder, or suffer from shift work sleep disorder, or their biological clock is malfunctioning causing their circadian rhythms to be disrupted, or they more rarely suffer from narcolepsy (sleeping during the daytime uncontrollably), or perhaps they suffer from restless legs syndrome or sleep apnoea. Then there’s classic insomnia which is the inability to sleep which encompasses all the above including anxiety and depression.
Living in the moment
Which leads me nicely to perhaps the main reason why cats and dogs tend to fall asleep so much faster than humans. Whereas humans tend to project their lives into the future and refer of the past and ask themselves too many questions about life which are impossible to answer, cats and dogs live in the moment. This is an innate characteristic which is one that humans should aspire to. In fact, psychiatrists and health gurus might advise an anxious person to try and live in the moment and not chew over problems too much.
World getting more complicated
But humans have a lot of lifestyle problems to deal with in an ever more complex world. There is no doubt that the world is far more complicated than it used to be. Looking back it all looks so innocent. Many people hanker after those days. In addition to the usual human anxieties which prevent them going to sleep sometimes, there’s a lot more that they can do before they go to sleep which keeps them awake such as social media communications. I’m sure many people go to bed with a computer or their smartphone by their side. It takes time for their brain to switch off afterwards. Companion animals don’t have this barrier to getting to sleep.
Also, many people don’t get tired enough partly because they don’t engage in enough physical activity. Physical activity is a great way to get tired in a physical way which puts you to sleep nicely. In conclusion, there’s a lot in the human way of life and mind which puts a brake on going to sleep quickly and which doesn’t apply to cats and dogs.
Cats snooze a lot – survival
Looking at the question from the point of view of cats and dogs, it is my experience with cats that they snooze lightly a lot and are not in deep sleep at that time. It is a fallacy to say that domestic cats sleep for huge length of time. They are snoozing and intermittently they enter into deep sleep from which they wake quickly if something disturbs them and threatens their security. This is a wild cat ancestor trait. They have to be constantly alert. Entering deep sleep quite quickly and waking equally quickly aids survival.
Secure and well fed
Actually, I’m not sure that cats and dogs do fall asleep any faster than a healthy, well exercised human but if they do, in a good home where they are well looked aftert, they are warm, they feel secure and they are well fed and loved. This creates a good environment which encourages good sleeping habits and patterns.
Humans forced into fixed sleep patterns
There are other factors worth mentioning. Humans divide up 24-hours into day and night time, two distinct blocks, normally. Cats don’t do this. They snooze, sleep and are active in a fragmented kind of way throughout twenty-four hours. People should learn from this. People should not try and shoehorn their lives into sleeping at night and doing something during the day. They should be more flexible and allow themselves to fall asleep when they feel like it and be awake when the body tells them to be awake if it’s allowed under their lifestyle. This idea would not work for somebody in the normal workplace.
Working from home
This is where the coronavirus pandemic comes in successfully. Employed people have to fit neatly into their employer’s work structure. When working at home, as many millions of people are, they can work more or less when they want to provided they are productive, which allows them to be far more flexible which should encourage more natural sleep whenever they feel like it.
Conclusion in round terms
The bottom line in answering the question in the title is that in a good home domestic cats and dogs won’t have much in their heads to stop them going to sleep in terms of anxieties et cetera and secondly they live in the moment which once again helps to empty the head. Both allow them to fall asleep relatively quickly.
Strays and wild cats and dogs
I have to add that for stray and feral cats I don’t think you can argue that they fall asleep much faster than humans. Survival is too difficult which keeps them awake and napping intermittently. Therefore the question in the title should be qualified by referring to “domestic dogs” and domestic cats”. One last point to make is that I’ve referred to domestic companion animals and not the wild cats and wild dogs because I believe that the question is about domestic cats and dogs.