As humans, we prefer to sleep at night and feel fresh during the day. But this is not due to habit we inculcate or based on any work schedules or convenience. It is driven by our own body clock. Circadian rhythm is just not about sleep, it regulates many physiological functions including Blood pressure, Body temperature, Hormone secretion, Sleep-wake cycle, Heart beat, Metabolism, Cell cycle, Response to drugs and many more.
Where is the clock?
The clock was first identified in Fruit flies. No doubt why Nobel prize winner Michael Rosbash said “I am very pleased for the fruit fly”.
Biological clocks are not made of cogs and wheels, but the area of the brain known as the suprachiasmatic nucleus is body’s master clock
A group of nerve cells in the brain called the suprachiasmatic nucleus, or SCN, situated right above the point in the brain where the optic nerve fibers cross, controls circadian rhythm. The SCN controls the body’s temperature, and small fluctuations in temperature throughout the day trigger various cells in different organ systems in the body to be sleepy or active. This is how the SCN controls the release of melatonin, the hormone that makes one sleepy. Genes are also involved in regulating body’s clock and circadian rhythms.
What Melatonin does
Durinh night more melatonin gets secreted. This hormone signals the brain to go into sleep mode. When the sun rises, melatonin secretion hits low, and the brain’s awake circuits restarts.
Is light important for Body clock?
Light is the signal based on which body clock functions. When the eye senses light, it sends signals to the SCN. This resets the clock every day. Our body does this to make sure rhythms do not drift out of line with the environment. Although our rhythms cycle happens about once every 24 hours, if we opt for total blindness, humans actually tick a little more slowly ie, about 24.1 hours. Thus, if we didn’t have daylight we would get out of synchrony with night and day. Precisely the reason because of which people in captive lose on day and night.
Things you did not know about Circadian rhythm
Do you feel sleepy post lunch. Blame it on circadian rhythm. Every day between 2 and 4 PM, the majority of the human race feels sudden sleepiness and a lack of focus. That’s because circadian rhythm goes down about 8 hours after wake up time. Some experts suggest taking a short power nap to get over this lull.
Teenager son or daughter suddenly behave like owls. Do not scream at them. Blame it again on circadian rhythm. As a teenage body goes through puberty, its circadian rhythm essentially shifts three hours backward. Studies of teenagers around the globe have found that adolescent brains do not start releasing melatonin until around eleven o’clock at night and keep pumping out the hormone well past sunrise.
It’s Circadian Rhythm that make you gain weight if you Snack at Midnight.