The surprising science behind waking up on the wrong side of the bed

Bad woman for upset sleep

New research using Fitbit data from over 2,500 medical interns found that mood cycles fluctuate with a nadir around 5am and a peak around 5pm Sleep deprivation was found to intensify these mood swings . The research highlights the critical role of the body’s internal clock in mood regulation and showcases wearable technology as a new method for examining mental health issues, providing insights into noninvasive monitoring of mood disorders and circadian rhythms in a clinical setting.

It’s always darkest before the dawn for many people, and now, a University of Michigan and Dartmouth Health study has examined the science behind waking up on the wrong side of the bed.

The study, which used Fitbit data from more than 2,500 doctors-in-training (trainees) over two years, found that trainees’ self-reported mood cycles reached their lowest point near 5 a.m. and their highest point around 5 a.m. high around 5:00 p.m. Lack of sleep made these moods. more intense swings, leading to worse moods and greater mood swings throughout the day.

Mood naturally cycles with its lowest point in the morning and highest in the evening, regardless of sleep deprivation. “Sleep deprivation is a distinct process that further lowers mood,” said Benjamin Shapiro, the study’s lead author and a psychiatrist at Dartmouth Health. “So someone who has been up all night at 5 a.m. should be in an even lower mood than if he woke up at 5 a.m., however, on a typical day his mood at 5 a.m. will be still lower than that in the evening.”

Study Methodology

The study, published in the journal PLOS Digital Health, analyzed data from 2,602 medical interns over a two-year period. The researchers measured the trainees’ continuous heart rates, step counts, sleep data and daily mood scores. The researchers also estimated wakefulness and circadian timing from minute-by-minute measurements of heart rate and movement.

“We found that mood follows a rhythm linked to the body’s internal clock, and the clock’s influence increases the longer one stays awake,” said Danny Forger, the study’s senior author and a professor of mathematics and computational medicine and bioinformatics at UM. Medical school. “The study highlights the important role our body clock plays in mood and introduces wearable technology as an exciting new way to explore these factors in mental health issues.”

Findings of mood assessment

Medical interns, part of the Intern Health Study, a multicenter study across the United States involving first-year physicians, also completed a once-daily assessment. Trainees could complete the assessment at any time during the day, and the assessment consisted of a single question: How was your mood today?

The researchers then plotted the participants’ mood scores against their circadian phase and against their time awake. They found that mood peaked at 5pm and dipped to its lowest at 5am. They also found that mood worsened the longer participants were awake.

“The field of psychiatry has known that sleep and circadian rhythm play an important role in mental health. However, these findings have only been shown in small samples and in artificial laboratory settings,” said Shapiro. “This study generalizes these findings to everyday life in a large number of participants.”

The researchers say that their study only looked at a generalized pattern of mood in medical trainees and that individual mood variation is more complex and dependent on factors such as social dynamics, schedules and temperaments. There were also minimal individuals who stayed awake for more than 18 hours in a day. Finally, the researchers did not use validated emotional assessment scales such as the Depression Anxiety Stress Scale or clinical screening tools.

But the researchers showed that noninvasive tools like Fitbits or other smart watches could be useful in tracking mood disorders and circadian rhythms.

“Instead of requiring invasive blood draws or temperature monitoring, we’re able to get similar data from a daily Fitbit,” Shapiro said. “This opens the door for mental health clinicians to use circadian rhythm measurements in daily clinical practice.”

Reference: “Uncovering the Interaction of Circadian Rhythm and Sleep Deprivation on Mood: A Real-World Study of First-Year Physicians” by Benjamin Shapiro, Yu Fang, Srijan Sen, and Daniel Forger, 31 Jan 2024, PLOS Digital Health.
DOI: 10.1371/journal.pdig.0000439

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