The finding suggests that physical activity may play an influential role in regulating mood and could therefore be a viable target for clinical intervention—a positive finding since physical activity is more easily changed than mood states.
Researchers from the University of Sydney and leading institutions in the US, France, Hong Kong and The Netherlands reported that increases in physical activity tended to be followed by increases in mood and perceived energy levels.
This beneficial effect was even more pronounced in a subset of the study subjects with bipolar disorder.
The findings challenge prevailing theories of depression proposing that sleep problems, low energy, and low activity levels are the result of depressed mood.
The study, which examined interactions among these factors, suggests the opposite may be true—that instability in activity and sleep systems could lead to mood changes.
Treatments that disrupt the body clock may be more likely to cause harm in patients.Professor Ian Hickie, Brain and Mind Centre, University of Sydney
- The researchers found bi-directional relationships between physical activity and subjective energy, and between physical activity and sleep duration.
- On average a higher activity level at one time-point was associated with improved mood and increased perceived energy at the next time-point during the day.
- Likewise, increased energy at one time-point was associated with increased activity at the next time-point. Importantly, these associations controlled for the current levels of mood, energy and activity, respectively.
- Activity was inversely associated with sleep duration—more activity tended to be followed by less sleep that night, and more sleep tended to be followed by less activity the next day.
- Tracking sleep, activity, mood and energy concurrently was particularly important in people with bipolar disorder because the changes in internal psychological states were strongly influenced by both sleep and physical activity.
Systems regulating sleep, motor activity and mood have typically been studied independently. This work demonstrates the importance of examining these systems jointly rather than in isolation.Dr Vadim Zipunnikov, Johns Hopkins University
“This study exemplifies the potential for combining the use of physical-activity trackers and electronic diaries to better understand the complex dynamic interrelationships among multiple systems in a real-time and real-life context,” said senior author, Dr Zipunnikov of Johns Hopkins University.
“Systems regulating sleep, motor activity and mood have typically been studied independently. This work demonstrates the importance of examining these systems jointly rather than in isolation.”
“Modern psychiatry is rapidly abandoning its traditional categories, such as major depression and bipolar disorder, in favour of personalised and more objective modes of assessment,” said study co-author, Professor Ian Hickie, of the University of Sydney’s Brain and Mind Centre.
“These then form the basis for more accurate predictions of illness course and, most importantly, choosing the most relevant treatments.
“They are also providing unique insights into probable underlying mechanisms.
“For bipolar disorder and atypical depression, they strongly support our working proposition that disturbed body clocks are the basic cause of these disorders—and that treatments such as physical exercise, light exposure, melatonin-based medicines—need to be much more specifically focused on stabilising the daily body clock.
“Treatments that disrupt the body clock, like some of the commonly-prescribed serotonin-based antidepressants may be more likely to cause harm in these patients.
“This study highlights the way our international consortium with nodes in USA, Europe, Australia, Canada, China and Hong Kong is using highly informative personal data, collected by 21st century personal technologies, to transform the diagnosis and treatment of the major mood disorders.”
Researchers used activity trackers and electronic diaries over a two-week period.
to collect data on physical activity, sleep duration, subjective mood and energy levels from study participants with bipolar-I disorder, bipolar-II disorder, major depressive disorder, or none of these three disorders.
The participants comprised 242 adults (150 women and 92 men), aged 15 to 84, including 54 people with bipolar disorder and 91 with major depressive disorder.