When you wake up in the morning, does it sometimes feel as though you’ve only been sleeping for a few minutes? Then you check the time and realize that 8 hours have passed in the blink of an eye.
Have you ever thought to yourself, why does time go by so fast when you sleep? I found myself thinking about this recently and decided to do some research on the topic.
In this article, I will take a deeper look into the parts of your brain and how they function during the different sleep cycles. My hope is that you will come away with a better understanding of why time can go by so fast when you sleep, in addition to the stages of sleep that can give you the feeling of time going by either faster or slower.
Let’s start with the main question on your mind.
The bad news is that you haven’t developed the ability to time travel while you were asleep. Time still passes at the same rate as when you’re awake, regardless of what you are experiencing in your sleep.
However, the amount of engagement your body and your brain have during each sleep cycle are what can give you the feeling of time passing either faster or slower.
As you pass through the different stages of sleep, which I will touch on next, your brain experiences different levels of activity. During sleep your brain isn’t being stimulated by all five of your senses, which our conscious mind uses as reference points in order to give us a sense of time.
The inner workings of your brain also undergo some changes during the night, which is known as the stages of sleep.
Your brain goes through sleep cycles multiple times per night, so it’s nothing to be afraid of. Most people naturally experience all the stages of sleep, therefore you’re not alone if you have the feeling that time is either speeding up or slowing down.
This is your brain’s transition from being awake to shutting your eyes and body down for sleep. During this stage, you can be easily woken up by noises or movements around you. Even having muscle twitches or changing positions is enough to jolt you awake again.
Entering a deeper sleep now, your body goes through a few physical changes that prepare you for entering a full, deep sleep. Your pulse slows down, your body temperature drops and you experience fewer and fewer active thoughts.
Slow-wave sleep kicks in at stage 3 as you enter the deepest form of sleep that your brain is capable of. The brain completely lets go of consciousness and starts to do all the overnight maintenance work that your body needs to recover for the next day. Think of this stage as the “dishwashing stage”. Your brain is clearing out all of the thoughts you’ve processed throughout the day. It is because of this stage that we are able to wake up clearheaded.
The final stage is called REM sleep, standing for ‘rapid eye movement’. This is your dream state where your brain has a similar level of activity to when you’re awake.
At stage 3, your brain has slowed down completely due to the presence of delta waves. Slow-wave sleep is essential for helping your body recover for the following day.
From repairing your muscles and tissues to boosting your immune system, slow-wave sleep is an important part of keeping you healthy and fresh.
Your brain blocks everything out as it prepares you for REM sleep (see also ‘What Does REM Sleep Stand For?‘). Without switching everything off before you start dreaming, your body would still be engaged enough to react during vivid dreams (see also our article on crying during sleep).
If you were dreaming about running, your legs would be moving while you were asleep.
During slow-wave sleep, time can feel as though it’s passing much quicker. At least when you wake up, this can be the case.
Due to your brain being completely disengaged, you have none of your usual reference points for time that you have when you’re awake. There’s no clock or sunlight, or additional sensory inputs to give you an impression of how much time has passed.
Slow-wave sleep can make it seem like you’ve blinked and hours have passed because there is nothing conscious happening in your brain.
REM sleep has the opposite effect as slow-wave sleep as your brain switches back on and experiences a lot of activity. Time can seem like it has slowed down during this stage as your brain enters its most active phase.
The levels of brain activity that you experience during REM sleep are similar to those that you have when you’re awake, which is why you’re able to have vivid dreams.
If you wake up in the middle of one of these stages, you will probably be able to remember your dreams in detail.
It is considered that we dream in slow motion, which is a simplified way of explaining the effects of REM sleep on time.
Have you ever had a dream that felt like it lasted for hours, but in fact it was only a minute or two? Dreams can really deceive your brain into thinking a lot of time has passed due to the activity that it goes through.
During the REM sleep stage, your brain can receive an overload of stimulation. This gives your brain a lot of potential reference points for the passing of time, which leaves you with the impression that hours have passed despite it only being a few minutes.
Time estimations during dreaming can vary wildly from person to person, and from dream to dream. Something that can effect your estimation of time while you are dreaming is the type of dream you are having and what state you are in.
Some dreams can feel like they have lasted an entire lifetime, while others feel like they last only a few minutes. Dreams can last as little as a few seconds and as long as an hour or more. On average, a majority of our dreams last 20 – 30 minutes.
It is fascinating to me how much dreams can have an impact on time perception. We know that during REM sleep, time seems to move faster. Later in the sleep cycle, you can experience “lucid dreams” or “waking dreams”, where most people have the experience that time seems to move slower.
The prevailing theory to the question “why does time go by so fast when you sleep” can be answered by two primary observations. First, that lower brain activity makes time seem to pass quicker, and second, that higher brain activity makes time seem to pass slower.
It can be difficult to wrap your head around this concept, conscious or otherwise, but your perception of time changes as your brain shuts down then boots up again.
The good news is, time still passes at the same rate as if you are awake, but it’s like watching the clock during a boring day at work. The more you focus on the hands ticking round, the slower time seems to pass.
A fun game to play is to see if you can guess how long you’ve been asleep the next time you stir in the night. Depending on the stage of sleep you’ve just experienced, it is entirely possible you will be completely off in your estimation.