In one recent study, scientists were able to explain why the sense of time with age is highly variable. As it turned out, there are several reasons that reveal the nature of the phenomenon.
In childhood time very long stretches. The lessons go on forever, like stretch and queues in shops. Already in 20-25 years the feeling of time accelerating. For old age people cease to notice how year after year there passes all life. Perhaps it happens because of the accumulation of domestic Affairs and concerns. However, there is another reason.
Scientists drew attention to the metabolism and vital signs. In childhood, the heart rate and respiratory rate are much higher than in adulthood. Metabolism in old age also slows down. These factors are likely to exert a strong influence on the sense of time.
Even in adulthood increases the amount of information that daily need to process. Everything else, after 20 years in the brain decreases the concentration of dopamine, the "happy hormone". This factor also has a significant impact.