Countermeasures can ease detrimental sleep effects of shift work

Key takeaways:

• One in five workers in the U.S. perform shift work.
• Shift work disorder is an extrinsic circadian rhythm disorder.
• Countermeasures can help achieve healthy sleep.

HONOLULU — Although shift work can lead to fragmented sleep and have circadian consequences, countermeasures can help overcome these negative effects and promote healthy sleep, according to a presentation at the CHEST Annual Meeting.

One in five workers in the U.S. perform shift work, in which the hours of work are outside of the normal workday, Nathan Nowalk, MD, pulmonary-critical care and sleep medicine fellow at University of Chicago, said during his presentation.

Such working patterns can lead to a condition called shift work disorder, he added.

“Shift work disorder is an extrinsic circadian rhythm disorder and that’s to say that it’s not something intrinsically wrong with the patient’s internal clock; it’s all due to desynchronization between the internal clock and external cues,” Nowalk said.

Consequences of shift work disorder

The criteria for shift work disorder include:

• insomnia and/or hypersomnia with a reduction of total sleep time;
• shift work schedule for at least 3 months;
• disturbed sleep-wake pattern on 14-day sleep log and actigraphy; and
• absence of any other condition to explain the sleep disorder.

This last point is particularly important, Nowalk said, because an intervention to address shift work disorder will fail if other sleep disorders, such as obstructive sleep apnea, are present.

Nowalk referenced a study published in 2011 in Sleep Medicine that showed that OSA severity worsens with shift work, as demonstrated by a higher mean apnea-hypopnea index (AHI) among shift workers with OSA during daytime sleep vs. night sleep (49.7 vs. 31.7), with their daytime AHI also being significantly higher than that of sleep-deprived controls (30.1; P < .05 for both)

“This highlights that this does worsen sleep apnea. Sleep fragmentation is trying to sleep during the day when you should be awake, and that’s a hallmark of shift work disorder. To see that within our sleep apnea patients and to see the difference in the AHI between these groups is an extreme finding and makes you wonder whether our PAP settings are correct for these folks; maybe AutoPAP isn’t fully addressing them.”

Countermeasures

Before the shift, it is essential to maximize sleep hygiene and schedule by reserving the bedroom for sleep, sleeping in a low-noise, light-free environment with minimal interruptions, and establishing regular wake time.

“These are obviously easier said than done, and there is no perfect answer for these things,” Nowalk said. “Often you'll find patients are limited simply by finances to achieve perfect environments.”

There is evidence for prophylactic napping right before the start of the shift, Nowalk added. Caffeine or stimulants also can be used before an extended commute or long shift, but Nowalk noted that a 2005 study on modafinil for shift work disorder had mixed findings. Results, published in The New England Journal of Medicine, showed that although the stimulant did reduce extreme sleepiness, there was still residual excessive sleepiness and impaired night performance among individuals assigned modafinil vs. placebo.

“It’s not a slam dunk that everyone should be using modafinil, but there may be a role for some particular folks and use of stimulants should be looked at on a case-by-case basis,” Nowalk said.

At work, countermeasures to address shift work disorder include using bright or blue lights during the shift, especially during the first half of the shift; planning in strategic and scheduled naps in a quiet dark space, lasting at least 10 minutes but no longer than 30 minutes, with use of caffeine before the nap to help prevent post-sleep inertia or grogginess upon waking; incorporating activity breaks; and consuming low and frequent caffeine in the first half of the shift.

After the shift, sunglasses should be used on the commute home, and a short nap can be taken at home if trying to change back to a daytime schedule. Caffeine should be avoided after the shift, as well as exercise within 1 hour of bedtime. If melatonin is used, it should be under the guidance of a physician so it does not further disrupt circadian rhythms, Nowalk said.

Employers can help support shift workers by “acknowledging sleepiness as human,” Nowalk said, in addition to having sanctioned workplace napping and adequate time off between shifts. Families can also help by minimizing noise and disruptions during quiet time and planning ahead for recovery days.

References:

• Czeisler CA, et al. N Engl J Med. 2005;doi:10.1056/NEJMoa041292.
• Paciorek M, et al. Sleep Med. 2011;doi:10.1016/j.sleep.2010.06.013.