A 37-year-old man comes to the office due to difficulty sleeping. He says that his new job as a business executive is very stressful and requires considerable travel. During the past 3 months, the patient has made numerous trips between the United States and France. He experiences insomnia and daytime sleepiness for several days after these trips, but his sleep then improves significantly. Which of the following hypothalamic nuclei is most likely responsible for this delayed improvement in his symptoms?

Question

A 37-year-old man comes to the office due to difficulty sleeping.  He says that his new job as a business executive is very stressful and requires considerable travel.  During the past 3 months, the patient has made numerous trips between the United States and France.  He experiences insomnia and daytime sleepiness for several days after these trips, but his sleep then improves significantly.  Which of the following hypothalamic nuclei is most likely responsible for this delayed improvement in his symptoms?

Quizplus · Accepted Answer

11ec160b_3cd0_c910_9249_fb682650f5a7_MD0001_00 This patient is experiencing jet lag, a syndrome associated with long flights that cross several time zones. Symptoms include insomnia, daytime drowsiness, decreased work performance, gastrointestinal issues, and generalized malaise. Jet lag is caused by dyssynchrony between the body's circadian rhythms (eg, sleep/wake cycle) and the local environment (eg, daylight hours, sleep schedules). Circadian rhythms are maintained by the suprachiasmatic nucleus (SCN). The SCN receives input from the retina and sends projections to other hypothalamic nuclei and the pineal gland. The primary functions of the SCN are to modulate body temperature and produce hormones such as cortisol (stress hormone) and melatonin (sleep-inducing hormone). Circulating melatonin levels are normally highest during the night and lowest during the day. In contrast, cortisol peaks in the morning and reaches its lowest level at night. In patients with jet lag, the suprachiasmatic nucleus eventually resynchronizes the body clock to coincide with the environment over the course of several days. Eastward travel takes longer to recover from than westward travel because it is easier to lengthen the natural sleep/wake cycle than to shorten it. Treatment with melatonin supplementation can improve the symptoms of insomnia associated with jet lag. Educational objective: The suprachiasmatic nucleus regulates circadian rhythms by processing light information from the retina and modulating body temperature and the production of hormones (eg, cortisol, melatonin). Dyssynchrony between the local environment (eg, daylight hours, sleep schedules) and internal circadian rhythms can cause insomnia and daytime sleepiness (ie, jet lag). Melatonin supplementation is recommended for the treatment of insomnia associated with jet lag.

A 37-Year-Old Man Comes to the Office Due to Difficulty