The health effects of shift work have been well studied. New research suggests that the ability to handle night shift work may be genetic.

Many health organizations, from the WHO to the CDC, consider working odd shifts a serious health risk and even a carcinogen. Labor experts estimate that 3.2 percent of the workforce works night shifts and another 2.5 percent work alternating shifts. Even more people work evenings, very early mornings and other odd shifts, totaling about 15 percent of the workforce in total. This means that around six million people are at higher risk of cancer, diabetes and heart disease. However, these risks appear to affect some people more than others.

The Trials of Shift Work

Shift work can be difficult to manage. People who work odd shifts are not awake at the same times as others, which can socially isolate them. Some people find it hard to sleep while it is light, leading to insomnia and other sleep disorders. Simply picking up a gallon of milk on the way home can be a challenge when you get off work at 2 a.m.

However, logistics are just the beginning of the challenges faced by some shift workers. In addition to the serious health risks, many report pervasive, constant fatigue and exhaustion. It was previously unknown why some people adjust quickly to night shifts while others seem to live mired in exhaustion. It ends up that a single gene may make all the difference for the nurses, police officers and other workers that keep our world running while we slumber.

Why Do Some People Handle Night Shift Better Than Others?

Researchers administered genetic testing to Finnish night shift workers and asked them to rate their fatigue on an ongoing basis. They then cross-referenced the genetic tests with symptoms. The results were interesting; the people who are less able to handle night shift work have a genetic variant for the gene for melatonin receptor 1A, a gene named MTNR1A.

The genetic variant that makes you less able to adjust to night work is caused by methylation of this receptor. DNA methylation is necessary for epigenetic gene regulation. This is significant because this particular receptor is known to be important in adjusting melatonin production according to the demands of one’s environment. It increases melatonin signaling when needed—but more so in people with a healthy version of the gene. The result is that people with the more methylated MTNR1A cannot quickly and effectively adjust their melatonin production to meet the needs of a different work schedule.

Making the Night Shift Work

The secret to making the night shift work, regardless of your genotype, is melatonin. Produced by your pineal gland and released in response to cues from the suprachiasmatic nucleus of your hypothalamus, this hormone cues your body to prepare for sleep. In addition, melatonin is important in signaling cells that you will be sleeping soon and that they can begin to undergo vital repair processes. Balancing your melatonin levels is key to getting the sleep you need, regardless of your work schedule. Here are a few ways to keep your melatonin levels and circadian rhythm in check:

• Get plenty of light during waking hours.
• Consider light therapy if bright natural light is not available when you are awake.
• Keep your sleep-wake cycle as consistent as possible.
• Talk to your physician about taking a melatonin supplement, particularly a long-acting supplement, if you often have to sleep at a time of day that differs from your own unique biological rhythm.

Melatonin is important to sleep, so it is not surprising that the ability to adjust melatonin levels is the crucial difference in how people handle night shift work. However, there are ways to maintain healthy melatonin levels and a healthy circadian rhythm even if you cannot always work days.