Can you sometimes "feel" what time it is without looking at a clock? Many people can, and that's because our brains operate on a schedule that follows a daily rhythm. Our chemistry therefore represents a sophisticated biological clock, and scientists are just now learning how to tell the time by reading our chemistry alone.

In fact, it may soon be possible to determine the precise hour of your death simply by looking at your brain's chemistry, reports the Smithsonian.

It sounds like a morbid exercise, but accurately determining the time of death could be a useful tool for forensic scientists. It could also reveal new information about how our brains function, which might lead to treatments for conditions like sleep disorders, dementia, depression and mental illness.

“Sleep and activity cycles are a very big part of psychiatric illnesses,” explained Huda Akil, a neuroscientist at the University of Michigan.

Akil has been at the forefront of the science behind how our bodies tell time. She recently studied the brains of 55 people who had died suddenly. Incredibly, the research allowed Akil and colleagues to determine the time of death of each brain within an hour of its actual death.

It turns out that the key to reading the brain's sophisticated clock lies in about 100 genes that ramp up their activity during certain times of day. The genes include those that dictate things like metabolism, lipid synthesis and wakefulness. The precise phase of these genes at the time of death can show the time of day they shut off, much like reading a busted wristwatch. For instance, people who died in the morning have a different mix of active genes and proteins in their brain cells than people who died in the evening or at night.

Of course, not everyone has exactly the same rhythm. There are night owls, morning birds, people who might work off hours, et cetera. But many of the key biological signifiers that keep the time within us are actually tuned to environmental, contextual stimuli, such as daylight. So even if not everyone keeps the same schedule, our internal clocks are still tuned to the universal rhythms around us. It's a complicated chemical puzzle, but it can potentially be deciphered regardless of your personal schedule.

How closely our personal schedules jive with the natural rhythms of our biological cycles could also have consequences on our long-term health. Though this science is still in its infancy, it could eventually provide evidence that the ways we mess with the natural rhythms of our circadian clocks could lead to many modern ailments, and possibly even contribute to neurodegenerative diseases.

Bryan Nelson ( @@brynelson ) writes about everything from environmental problems here on Earth to big questions in space.

Your brain chemistry could reveal the hour of your death
When we die suddenly, our circadian rhythms stop abruptly like a broken wristwatch, revealing the time of death.