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SLEEP
MEDICINE

Jet Lag: Falling Asleep with Diamonds

By Rajam Ramamurthy, MD

T he Lufthansa flight landed in Mumbai, India at 1:00 a.m. The every 24 hours and controls our sleep-wake cycle. The anterior hypo-

passengers were wide awake after traveling from San Antonio
thalamus is an area in our brain where the suprachiasmatic nucleus
via Chicago and Frankfurt for 21 hours halfway around the
acts to external cues like light and darkness, and synchronizes the body’s
world. You can think that the Indian Standard Time (ISD) is exactly (SCN), a pair of distinct neuronal clusters, is located. This tiny area re-
12 hours ahead of our central time plus-minus 30 minutes to an hour internal clock with the external environment in peripheral tissues and
and a half based on our daylight savings time. Yes, according to my San other brain regions. The scientific name for jet lag is “Desynchronosis.”
Antonio time, I was wide awake in the middle of the afternoon. After Light is sensed by the ganglion cells in the retina that convert the pho-
clearing the customs and immigration formalities, I boarded the flight ton energy into an electrical signal. This is directly projected onto the
to Bengaluru (formerly Bangalore), which I reached at 6:00 a.m. ISD. SCN regions of the brain, which will influence the secretion of mela-
At 9:00 a.m., I spoke at the Indian Academy of Pediatrics National tonin. These signals maintain a consistent rhythmic order of the bio-
Conference. I was satisfied with my presentation and enjoyed the deli- logical processes.
cious lunch, the local cuisine, which is my hometown, and meeting so Experimental, bilateral ablation of the hypothalamus in rodents, pi-
many friends, colleagues and medical students. In the afternoon, I was tuitary tumors and human vascular disease could disrupt the circadian
on a panel. Uncontrollable fatigue overtook me, and I woke up with a control of behavior, and metabolic and endocrine functions. The mis-
jolt when my head dropped on my shoulder; it was past my usual bed- alignment causes a disturbance in the secretion of the hormone mela-
time in San Antonio, 1:00 a.m. Jet lag, I thought. I did manage the rest tonin, which regulates sleep — thus, there is interest in melatonin as a
of the day tired, with low energy and a royal headache, all symptoms treatment modality. Sleep deprivation, as happens in night shift work-
of jet lag. At about the same time, my spouse had a scrumptious break- ers, late-night eating for the same reason, and chronic jet lag, with fre-
fast prepared by his sister, with whom we stayed. He slept from 9:00 quent international travels, has led to a public health crisis. Mood
a.m. till 5:00 p.m. ISD, which coincided with his San Antonio sleep disorders, obesity, diabetes and cancer are found to be associated with
time and was bright and cheerful at dinner. However,
I was completely adjusted to the ISD the following
day, and he could not sleep at night for the next few
days. I was in bright daylight, and he was still in the
U.S. zone. People often marveled at my ability to jump
into a working mode. Yes, the pressure of work, not to
minimize my compulsive shopping spree when I was
in India, kept me awake. The same disruption happens
upon returning home to San Antonio; however, it is
not so pronounced. This may be partially due to the
necessity of work and other chores. It is also known
that jet lag is worse with travel to the east.
What is jet lag? Jet lag, or flight fatigue, is a tempo-
rary disruption of the body's internal biological clock
caused by rapid travel across multiple time zones. Our
circadian rhythm (the body’s internal clock), which
regulates the sleep-wake cycles, becomes misaligned
with the external environment, the presence of dark-
ness and light.
Delving a little into physiology, the circadian
rhythm is a natural physiological process that repeats

20 SAN ANTONIO MEDICINE • March 2024