“Until now, no clinical trial had tested a treatment for shift work disorder in early-morning shift workers, even though this is the most common type of shift schedule,” said senior author Charles A. Czeisler, PhD, MD, chief and senior physician of the Division of Sleep and Circadian Medicine in the Mass General Brigham Department of Medicine. “This study addresses a major gap by focusing on the workers who start their day when most people are still asleep.”

Why Early Shifts Disrupt the Body’s Clock

Roughly one in four workers operates outside the standard 9 to 5 schedule, including those who begin work very early in the morning. Many people with these schedules do not consider themselves shift workers and instead see their routine as simply starting the day earlier than usual. However, they may still face a high risk of shift work disorder, which involves disrupted sleep patterns and persistent daytime sleepiness.

“People who start work between 3 a.m. and 7 a.m. are waking up at a time when the brain is biologically programmed to sleep. That makes staying alert extraordinarily difficult, even when they are highly motivated,” said first author Kirsi-Marja Zitting, PhD, an investigator with the Division of Sleep and Circadian Medicine in the Mass General Brigham Department of Medicine. “They are often dealing with a double burden — excessive sleepiness during work hours and difficulty sleeping enough when they have the chance to rest.”

Health and Safety Risks of Shift Work Disorder

Shift work disorder is linked to a range of serious concerns, including reduced mental sharpness, lower productivity, increased risk of car accidents, and more workplace injuries. Medications such as modafinil are sometimes used to promote wakefulness, but these drugs have mainly been studied in overnight workers and can interfere with sleep later in the day.

Solriamfetol, the drug evaluated in this study, is already approved for treating excessive sleepiness in people with obstructive sleep apnea and narcolepsy. Researchers considered it a promising option because it can promote alertness for extended periods without significantly disrupting later sleep.

Clinical Trial Shows Improved Alertness and Performance

The study included 78 early morning shift workers diagnosed with shift work disorder. Participants were randomly assigned to take either solriamfetol or a placebo on workdays over a four-week period. Researchers assessed their ability to stay awake in a controlled, low-stimulation setting during hours that matched their typical work schedule. Participants also reported on their daily functioning and met regularly with clinicians.

After four weeks, those who received solriamfetol showed clear improvements. They were less sleepy and could remain awake longer during simulated work hours. Both participants and their doctors noted better overall functioning, improved work performance, and greater ability to manage daily tasks.

“The improvement we saw is clinically meaningful. These workers were able to stay awake and alert throughout a full eight-hour shift, which has real implications for performance, safety, and quality of life,” Czeisler said. “Shift workers are essential to how our society functions, yet they often pay a hidden biological cost. This study shows we can do better for them.”

More Research Needed on Long-Term Effects

The researchers emphasized that early morning shift workers have not been widely studied, and the current trial lasted only four weeks and included otherwise healthy adults. More research will be needed to understand the long-term effects of the treatment. The team is now enrolling participants for a follow-up clinical trial to study solriamfetol in overnight shift workers, which could help support broader approval for treating shift work disorder.

In addition to Zitting and Czeisler, Mass General Brigham authors include Katherine R. Gilmore, Brandon J. Lockyer, Wei Wang, Nicolas C. Issa, Stuart F. Quan, Jonathan S. Williams, and Jeanne F. Duffy. Additional authors include Eileen B. Leary.

Funded by Jazz Pharmaceuticals, Axsome Therapeutics, and Brigham and Women’s Hospital Center for Clinical Investigation; NCT04788953(2021-03-09) https://clinicaltrials.gov/study/NCT04788953