Symptoms of Jet Lag
If you are planning a vacation or a business trip which requires flight across multiple time zones, you may want to prepare yourself for jet lag. Jet lag is when a person’s internal circadian rhythm is out of sync with external day-night rhythm of their new location. The symptoms of jet lag include:[1]
- Fatigue upon arrival in new time zone
- Sleep issues
- Reduced alertness and cognitive skills
- Low mood
Jet lag can also intensify existing mood issues and the severity of jet lag symptoms increases with the number of time zones crossed.[2] This could have a negative impact on your work performance and overall health.
The Human Body’s Circadian Rhythm
So, what can you do to avoid this unpleasant phenomenon while traveling? First you must understand the body’s circadian rhythm and how it can be disrupted.
The human circadian rhythm is a 24-hour cycle in core body temperature, circulating hormones, and sleeping/waking activity.[3] It is regulated by the SCN (suprachiasmatic nuclei) which are part of the hypothalamus.
The SCN controls the secretion of the body’s primary sleep hormone, melatonin. Melatonin is produced and released from the pineal gland in the brain.[4] Sleep is most easily achieved during the phase of the circadian cycle when body temperature is lowest and melatonin secretion is highest.[5]
This internal clock is not easily changed. This is why you can take a nap during the day or wake up in the middle of the night without your entire sleep schedule becoming disrupted.[6]
Zeitgebers
However, the internal clock can be effected by cues in the environment that indicate time called zeitgebers.[7] The two main zeitgebers are the light-dark cycle of the sun and the secretion of melatonin which takes place at night, during sleep in healthy people.[8]
The SCN have melatonin receptors and receive information about the presence or absence of light from our eyes.[9] Based on this information the circadian rhythm can be altered. These alterations are called phase shifts, and can either advance or delay the natural circadian cycle.[10]
Circadian Misalignment
When traveling west you will experience a phase delay and difficulty staying asleep at night. On the other hand, when traveling east, you will experience a phase advance and have difficulty initiating sleep.[11] The symptoms of jet lag are caused by phase shifts in your circadian rhythm, or circadian misalignment. Correcting this condition is extremely important!
Circadian Misalignment and Metabolic Function
Many studies reveal that even short instances of circadian misalignment impairs metabolic functions and increases the risk of cardiovascular disease and Type II diabetes.[12] If you are a regular traveler who has chronic circadian misalignment, you also have an increased risk of gastrointestinal and immune issues.[13]
Now that you understand what is going on, what can you do to deal with phase shifts and the symptoms of jet lag that they produce?
Melatonin and Jet Lag
One of the simplest and effective methods is taking melatonin. In one study 5 mg of melatonin was given to subjects in the evenings for 3 days before their flight, and then at bedtime in the new time zone for 4 days after their flight.
Self-ratings of jet lag symptoms, sleep, and mood, as well as measures of melatonin and cortisol rhythms improved faster in those that received melatonin as compared to the placebo.[14]
A meta-analysis of melatonin studies found that 9 out of ten trials showed decreased jet lag symptoms when subjects took melatonin close to the bedtime in the new time zone they were traveling to.[15] Oral administration of melatonin has also been shown to lower core body temperature, further easing ability to fall asleep.[16]
Advice to Overcome Jet Lag
Here is the important advice you’ve been waiting for:
- If you are traveling east, you should phase advance your circadian rhythm which can be achieved by taking melatonin in the afternoon or evening.[17]
- If you are traveling west, you should delay your circadian rhythm by taking melatonin late at night or early in the morning.[18]
Studies indicate that between 0.5 and 5 mg is the most effective dose.[19]
Be aware, the timing of your melatonin dosage is important! If you take it at the wrong time of day, it can further prevent adaptation to the new time zone you are traveling to.[20]
This highly effective, natural sleep hormone can help realign your circadian rhythm. As well as decreasing the symptoms of jet lag, a healthy circadian rhythm supports blood sugar management and cardiovascular health, and prevents the worsening of mood issues. Have an enjoyable and productive time as you travel this holiday season!
Resources
[1]Srinivasan V, Spence DW, Pandi-Perumal SR, et. al. (2008). Jet lag: Therapeutic use of melatonin and possible application of melatonin analogs. Travel Medicine and Infectious Disease, 6, 17-28.
[3] Ibid.
[4] Srinivasan op. cit.
[5] Srinivasan op. cit.; Waterhouse op. cit.
[6] Waterhouse op. cit.
[7] Srinivasan op. cit.; Waterhouse op. cit.; Sack op. cit.
[8] Ibid.
[9] Waterhouse op. cit.
[10] Ibid.
[11] Srinivasan op. cit.
[12] Crowley SJ & Eastman CI. (2013). Melatonin in the afternoons of a gradually advancing sleep schedule enhances circadian rhythm phase advance. Psychopharmacology, 225, 825-837; Crowley SJ & Eastman CI. (2015). Phase advancing human circadian rhythms with bright light, afternoon melatonin, and gradually shifted sleep: can we reduce morning bright light duration? Sleep Medicine, 16, 288-297.
[13] Crowley (2013). op. cit.
[14] Srinivasan op. cit.
[16] Waterhouse op. cit.; Sack op. cit.
[17] Srinivasan op. cit.; Crowley (2013). op. cit.
[18] Srinivasan op. cit.
[19] Caspi op. cit.; Crowley (2013). op. cit.
[20] Caspi op. cit.
Clinical Contributor
Marina Braine
Clinical Support Specialist at Sanesco International, Inc.
Marina Braine is a Clinical Support Specialist at Sanesco. She graduated from UNC-Asheville with her Bachelors of Science in Biology with a minor in French. She likes to keep active by hiking, running, and contra dancing around Asheville.
