Our moods naturally cycle from their lowest point in the morning and highest in the evening, and this is independent of sleep deprivation.
Benjamin H. Shapiro, MDIf you want to avoid waking up in a bad mood, try hitting the snooze button. According to a new Dartmouth Health and University of Michigan study, a 5 am wake-up call may be worth sleeping through.
Using Fitbit data from more than 2,500 medical interns over two years, the study uncovers some eye-opening science behind circadian rhythms. Published in the journal PLOS Digital Health, the study found that the interns’ self-reported mood cycles hit their lowest point nearing 5 am and highest point around 5 pm. Staying awake for long periods of time made mood swings more intense throughout the day.
“Our moods naturally cycle from their lowest point in the morning and highest in the evening, and this is independent of sleep deprivation,” said Benjamin H. Shapiro, MD, lead author of the study and psychiatry resident at Dartmouth Health’s Dartmouth Hitchcock Medical Center. “The study suggests someone who’s been awake all night at 5 am should have an even lower mood than if they just woke up at 5 am. However, on a typical day, their mood at 5 am will still be lower than it is in the evening.”
Researchers measured the interns’ continuous heart rate, step count, sleep data and mood scores. They also estimated circadian time and time awake from minute-by-minute wearable heart rate and motion measurements. As part of the Intern Health Study, a multicenter study across the United States involving first-year physicians, the interns also completed a daily assessment consisting of a single question: How was your mood today?
The data from the mood scores were then plotted against their circadian phase and their time awake. In addition to learning more about biorhythms, the study also underlines the value of wearables as a means of tracking mood disorders.
“Instead of resorting to invasive blood draws or body temperature monitoring, clinicians are able to obtain similar data from an everyday Fitbit,” Shapiro says. “In mental health care settings, this opens the door for utilizing circadian rhythm metrics in everyday clinical practice.”
Our internal clocks seem to be naturally set for just how bright-eyed and bushy-tailed we might expect to feel at any given time of day.
“The study highlights the significant role our body’s clock plays in mood and introduces wearable technology as an exciting new way to explore these factors in mental health issues,” said Daniel B. Forger, PhD, senior author of the study and a professor of mathematics and computational medicine and bioinformatics at the University of Michigan Medical School.
Although the study only looked at a generalized model of mood in medical terms, individual variation of mood is more complex. Other factors, such as social dynamics, schedules, and temperaments, all play a role in mental health. In addition, this study had few participants who stayed awake more than 18 hours during a day. Furthermore, the researchers did not use validated emotional rating scales such as the Depression Anxiety Scale or clinical screening tools. Still, the findings seem to suggest we shouldn’t lose sleep if we’re waking up on the wrong side of the bed
About Dartmouth Health
Dartmouth Health, New Hampshire's only academic health system and the state's largest private employer, serves patients across northern New England. Dartmouth Health provides access to more than 2,000 providers in almost every area of medicine, delivering care at its flagship hospital, Dartmouth Hitchcock Medical Center (DHMC) in Lebanon, NH, as well as across its wide network of hospitals, clinics and care facilities. DHMC is consistently named the #1 hospital in New Hampshire by U.S. News & World Report, and recognized for high performance in numerous clinical specialties and procedures. Dartmouth Health includes Dartmouth Cancer Center, one of only 56 National Cancer Institute-designated Comprehensive Cancer Centers in the nation, and the only such center in northern New England; Dartmouth Health Children’s, which includes Children’s Hospital at Dartmouth Hitchcock Medical Center, the state’s only children’s hospital, and multiple clinic locations around the region; member hospitals in Lebanon, Keene and New London, NH, and Bennington and Windsor, VT; Visiting Nurse and Hospice for Vermont and New Hampshire; and more than 24 clinics that provide ambulatory services across New Hampshire and Vermont. Through its historical partnership with Dartmouth and the Geisel School of Medicine, Dartmouth Health trains nearly 400 medical residents and fellows annually, and performs cutting-edge research and clinical trials recognized across the globe with Geisel and the White River Junction VA Medical Center in White River Junction, VT. Dartmouth Health and its more than 13,000 employees are deeply committed to serving the healthcare needs of everyone in our communities, and to providing each of our patients with exceptional, personal care.