All facts of jet lag

Jet lag is also known as circadian desynchrony.Desynchrony is a condition in which the environmental cues and patterns conflict with an individual’s existing pattern. And that’s exactly what’s going on when we experience jet lag | there’s a mismatch with the body’s natural circadian rhythm and the external environment as a result of travel across time zones.

In order to fully understand what happens to the body when experiencing jet lag, you must first understand the role of the internal circadian clock. The central circadian clock is located in the suprachiasmatic nucleus of the hypothalamus. This is where light signals from the retina are received. The suprachiasmatic nucleus is responsible for adapting the circadian rhythm according to the light-dark cycles of the environment and generating neuronal and hormonal activities that regulate various body functions in a 24hours cycle. "2"

The suprachiasmatic nucleus initiates the actions of the pineal gland, which starts to make melatonin that’s released into the bloodstream. Within the pineal gland, serotonin, a neurotransmitter that’s derived from the amino acid tryptophan, is processed to yield melatonin. When melatonin levels increase, we begin to feel more sleepy, and when our circadian rhythms are running normally, melatonin levels remain elevated while we sleep for approximately 12 hours.Then melatonin levels drop again in the morning, remaining that way throughout the day.

Daily rhythms are evident in most aspects of our physiology, and they are driven by our internal timing systems, or circadian clocks.Our environment provides rhythmic cues, called zeitgebers,that synchronize the internal body clock to the Earth’s 24-hour light-dark cycle. Although light is the strongest environmental cue received by the body, other cues include temperature, meal timing, social interaction, exercise and even the effects of medication.

This explains why blind people typically have free-running sleep/wake cycles, which can be extremely burdensome if a synchronizing treatment is not applied. Because they have no perception of light, their endocrine,metabolic,behavioral and sleep patterns are inconsistent. "3"