Why People Perceive the Passage of Time Differently
Although physical time moves at the same rate for everyone, our individual perception of it can vary greatly. If seconds on a clock ticked more slowly, then days and the entire calendar would shift accordingly. For humans, however, it doesn’t work that way. Different biological mechanisms are responsible for different intervals of time. One mechanism governs micro-intervals lasting tens of milliseconds—for example, determining whether we can distinguish two events or if they blend together. Another mechanism defines the interval we perceive as the subjective present. When we move beyond the scale of hours, declarative memory comes into play—how we recode events. Yet another mechanism is responsible for circadian rhythms—changes in the body related to the day-night cycle. While these mechanisms interact, they are still distinct: a faster rate of event merging doesn’t mean a person’s sleep-wake cycle will also speed up.
The perception of time in micro-intervals is linked to the neurotransmitter dopamine, while intervals of several seconds are associated with serotonin. Certain genes are functionally connected to the work of the serotonergic and dopaminergic systems, respectively. Depending on the gene variant, a person may have more or fewer receptors for serotonin or dopamine. The same goes for the reuptake of these neurotransmitters into the cell—it can be more or less efficient.
We conducted an experiment dividing people into groups with genetically predetermined higher or lower activity of the serotonergic system. Participants took a simple test: they had to compare the duration of two stars shown on a screen. First, one star appeared for a few seconds, then the other. They had to answer which star was shown longer. It’s known that most people, when shown two stars for equal durations, will say the first one was shorter. This happens because time perception gradually contracts; as events recede from the present, they seem shorter. We calculated by how much this perceived time shortens. For one person, the first star would need to be shown for 6 seconds and the second for 4 seconds to be perceived as equal; for another, 4.5 and 4 seconds. This creates a continuum: for some, time contracts faster, for others, more slowly. We found that the groups did indeed perceive time differently: those with more active serotonin had a faster internal clock.
Similar psychopharmacological experiments have been conducted: participants were given microdoses of psilocybin, which activates 5-HT2A serotonergic receptors. Such small doses do not alter consciousness, and people remain fully aware, but their perception of time changes in the same way as in our experiment—depending on serotonin levels.
How Night Owls Differ from Early Birds
There are also genetic factors influencing how we perceive day and night cycles. The day is 24 hours long, and all bodily processes adjust to this cycle, with hormone levels, cortisol, and other factors changing according to the time of day. However, some people have a slightly shorter cycle—about 23 hours—while others have a longer one, up to 25 hours.
The well-known division into “early birds” and “night owls,” who are most productive at different times and have different perceptions of when it’s time to sleep, is also linked to genes and our perception of time. We conducted a mini-project at the Sirius camp, dividing students into groups of night owls and early birds. We then observed how each group solved problems in the morning and evening and assessed their productivity. It turned out that productivity was linked to time perception: night owls judged time more accurately in the evening, while in the morning, time seemed to “stretch out” for them; for early birds, it was the opposite.
There are also extreme cases. In 1999, an American psychiatrist first described families who came to him complaining of depression: they said they fell asleep very early, around 7 p.m., which prevented them from participating in social life, and they couldn’t do anything about it. Naturally, they also woke up very early. Several such families were found, allowing for genetic analysis, which identified a gene (called the period gene) associated with circadian rhythms. Interestingly, this gene had previously been identified in fruit flies and mice, where it also determined the length of the sleep-wake cycle. Certain mutations can completely disrupt this cycle, making it unrelated to external changes like day and night, while in other cases, as in these families, the cycle was 23 instead of 24 hours, leading to chronic shifts toward earlier activity and evening exhaustion.
Whether you’re a night owl or an early bird is determined by your genes, but that doesn’t mean you can’t influence it. There’s a concept called epigenetics—the interaction of external and genetic factors. Lifestyle has an impact, and various psychological techniques can help; for some, change comes more easily than for others, but generally, people can adapt, sometimes with extra effort. As we age, our perception of time and sleep patterns also change: you might be a night owl in youth and become an early bird later in life.
How Time Perception Affects Us
Many researchers have tried to find connections between time perception and individual personality traits. There’s a hypothesis that the classic division of temperament—sanguine, choleric, phlegmatic, and melancholic—is related to how a person perceives time. In one experiment, participants were given tests to estimate one second and compared on how they perceived the passage of time, then these characteristics were correlated with temperament traits.
In tests like the famous marshmallow experiment—whether a person is willing to wait for a delayed reward or prefers a smaller reward immediately—the choice is often linked to cognitive effort. But another factor is how quickly time seems to pass for the person: for some, the interval flies by, while for others, it drags on. This also influences decision-making.
It’s possible that differences in time perception explain why some people are often late (those with more serotonin and a faster internal clock), while others are more punctual. However, the reason for lateness can also be the opposite: people perceive waiting differently. Some arrive early and wait calmly, while for others—those with lower serotonin—waiting is so unbearable that they do everything to avoid it, which can make them late.
We are currently studying the relationship between decision-making, impulsivity, and the perception of time. We also want to explore the link between time perception and depression, since similar genes are associated with both processes in the literature—it’s logical to assume that time perception also plays a role. It’s also known that depression can alter the experience of time.