This lesson will give you some answers. There is a mini-quiz at the end of this lesson. We have devices to measure time, such as clocks. But it is not clear where the sensor for time is within the human or animal body. Certainly there is a biological clock that indicate when you grow, mature, get old and die, but it cannot be pinned down as a detector of some outside energy, as with the other senses.
Some people can use an inner clock to wake themselves up in the morning.
I've done in some special situations where I had to get up early, but I did not have an alarm clock handy. Sure enough, I woke up on time. The only problem with doing that, I found, is that your sleep is not very sound. You can also get a sense of time passing, but most people are not sure how they sense it. Relative time As people get older, they notice that time goes by more quickly.