Time perception during sleep often seems different from that of our waking hours.
Sleep experts recommend getting at least 8 hours of rest a night, and a typical working shift also lasts 8 hours. Our time in bed seems to move much faster, though.
Time moves at the same rate, regardless of whether we’re awake or asleep.
The third of the four sleep stages is called slow-wave sleep. During this stage, we have little brain activity. This disengagement from thought processes and consciousness means that time seems to race by.
If you wake up feeling groggy or unrested in the morning, it doesn’t mean time moved differently while you were asleep. The sleep cycles you undergo influence your perception of time.
Does Time Move Differently When We Sleep?
Time is linear. If you run a stopwatch for 1 minute, those 60 seconds will run for the same time, whether you’re awake or asleep. If you doze off for that minute, the time will seem to pass in the blink of an eye.
We’re relaxed and not paying attention to our surroundings when we sleep. As a result, time seems to pass faster. However, if you’re aware that you’re being timed, you’ll likely feel every moment passing.
Part of this is down to relativity. Albert Einstein, the founder of the theory of relativity, allegedly summarized this with a famous quote:
“When you sit with a nice girl for 2 hours you think it’s only 1 minute, but when you sit on a hot stove for 1 minute you think it’s 2 hours. That’s relativity.”
Albert Einstein
Here’s another example, more directly related to sleep. If you go to bed at 11 pm, and fall asleep instantly, the next time you glance at your clock, it may well be 3 am or 4 am. If you’re lucky, you won’t even need to recheck the time until morning.
If you can’t sleep, insomnia has struck, and time will likely feel very different. Lying in bed with your eyes closed and growing increasingly frustrated at being awake, you may think that hours have passed, and in reality, it will only be 11.30 pm.
Understanding that time doesn’t move faster while we sleep is important. All the same, we can use sleep to pass the time and bring about a rapid transition into a new hour or day.
Why Does Sleep Feel So Short?
As mentioned, sleep appears to make time move faster. Many of us learn this as children. When we have something to look forward to, getting to bed early seems to bring about the next day sooner.
Think of a good night’s sleep as akin to an operation that requires a general anesthetic. When we’re in the OR and feeling the effects of the sedative, our eyes will close, no matter how much we fight it. The next thing we know, we’re awake and in the recovery ward.
We could have been under the influence of anesthesia for just thirty minutes or as long as ten hours. The outcome is the same: we won’t remember or notice that we were asleep during the procedure.
The same applies when we fall into a deep and restful slumber at night. If we manage to sleep the entire night, not needing to use the bathroom overnight or rise for any other reason, the distance between bedtime and the sound of an alarm can feel like seconds.
Not all sleep stages appear to speed up time in this fashion, though. Slow-wave sleep is the most critical component to making sleep feel like a way to speed up time. This is one of the four stages of sleep that we all go through each night in bed.
What Are The Four Stages of Sleep?
Whenever we sleep, the body and brain cycle through four disparate stages, which are as follows:
| Stage 1: | This is the first few moments after you close your eyes. You can be roused from slumber by the slightest noise or nudge and may experience involuntary muscle twitches and jerks. |
| Stage 2: | You start to fall into a deeper sleep. Your heart rate slows, your body temperature cools a little, and your thought processes are much less active. |
| Stage 3: | Also known as slow-wave sleep, your brain is wholly disengaged while your body repairs damage and wear and tear. This is the deepest sleep that we experience. |
| Stage 4: | REM sleep is when your brain re-engages, and you experience dreams. Time feels longer at this point of sleep, especially compared to stages 3 and 4. |
These stages will repeat multiple times throughout your time in bed, and each is equally important. The third stage is what governs our perception of time while we sleep.
What Is Slow-Wave Sleep?
Slow-wave sleep, called deep sleep, could be considered downtime for the brain. This stage of sleep, which sees the brain release delta waves, is a preparation for the fourth and final stage of sleep to follow – rapid eye movement (REM) sleep.
The Journal of Clinical Sleep Medicine explains that slow-wave sleep is arguably the most critical sleep stage. Deep sleep allows the body to relax and repair itself and improves the chances of feeling refreshed and alert in the morning.
Think of slow-wave sleep as an opportunity to recharge your batteries. Your cellphone will cease working if you don’t place it on charge overnight, and the same applies to the human body and brain.
Rest is essential to keeping everything running as it should.
Why Does Slow-Wave Sleep Impact Our Sense of Time?
This all comes back to our earlier discussion about relativity. Time seems to have no meaning if you’re disengaged from the world around you. If you’re focused on something, seconds feel like they drag.
Examples of this can be found in many different walks of life, not just in sleep.
Picture any of the following scenarios:
- You walk into a movie theater at 7 pm while it’s light outside. You leave at 10.30 pm, and it’s dark out. You were engaged with watching the movie throughout this time, so you didn’t notice the time pass.
- You practice meditation or other acts of mindfulness. During this time, you are disengaging your mind in its entirety. According to Consciousness and Cognition, this alters your perception of time.
- You’re extremely busy at work, barely having time to stop and drink a coffee or use the bathroom between tasks. Before you know it, your shift is over, even though it feels like you have just started.
Whatever you do to pass the time, you’ll likely cease to watch the clock. This, in turn, will make time seem to move faster, while the opposite is also true. As the popular adage claims, “a watched pot never boils.”
Does Sleep Feel Longer When We Dream?
Having established that slow-wave sleep is the third stage of our sleep cycle, REM sleep is the fifth and final. REM sleep is the period in which we dream. The body cycles in and out of REM throughout our time in bed.
The American Journal of Physiology explains that REM sleep varies in length. Your first cycle is likely to be as short as ten minutes. When your body is in its final REM stage of the night, it could last as long as an hour.
It’s commonly believed that humans dream in slow motion. Theories as to why this may vary, though the most prominent is that the brain continues to work slowly while we’re in REM sleep.
We’re still asleep, but our perception of time will shift. While we undergo REM sleep and dream, rest can feel considerably longer, especially if we recall our dreams in the morning. A particularly vivid dream can feel like it lasted hours.
This may contribute to us waking up feeling unrested, despite sleeping for the recommended eight hours. If you had a series of nightmares during your REM sleep cycle, you would not have enjoyed a great deal of restful slumber.
Equally, you may have dreamt about physical activity, and your body reacted while you slept. Suppose you dreamt about running a marathon. You may have kicked your legs in your sleep and feel the physical after-effects in the morning.
Unfortunately, you won’t automatically enjoy the endorphins that accompany such exercise, as you’ll need to stretch for that to happen. Whether you recall five dreams in an evening or none, time moved at the same speed while you were dozing.
Getting to bed early can bring about a new day much faster. It depends on whether you enjoyed enough restful sleep and what sleep stages dominate your time in bed. Just remember that an hour asleep or an hour awake both contain sixty minutes, regardless of how it feels.
