If you work shifts or have an inhumanely early alarm clock, you’ll be familiar with the feeling of shuffling around in the dark while it feels like the rest of the world is still tucked up in bed.
Well it turns out you’re actually not alone, because scientists have discovered that 5am is officially the worst time of the day.
In a study of more than 2,500 participants, researchers from the University of Michigan and Dartmouth Health found this was the time when people reported their lowest moods – compared to 5pm, when they were most cheerful.
The 5am dip was also present regardless of when the participants got up – but their mood was worse the longer they had been awake.
‘Mood naturally cycles with the lowest point in the morning and highest in the evening independent of sleep deprivation,’ said lead author Dr Ben Shapiro, from Dartmouth Health.
‘Sleep deprivation is a separate process that further decreases mood. So someone awake all night at 5am should have an even lower mood than if they just woke up at 5am. However, on a typical day their mood at 5am will still be lower than that in the evening.’
The study, published in the journal PLOS Digital Health, used Fitbit data from 2,602 medical interns over two years. Each smart device allowed researchers to measure participants’ heart rate, step count, sleep data and daily mood scores.
The team also estimated circadian time – the body’s natural clock – and time awake.
Senior author Professor Danny Forger, from the University of Michigan, said: ‘We discovered that mood follows a rhythm connected to the body’s internal clock, and the clock’s influence increases as someone stays awake longer.
‘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.’
In addition to wearing Fitbits, the interns completed a daily assessment, at any time, asking ‘How was your mood today?’. Mood was measured on a scale of one to 10.
The results not only highlight the dips and peaks at 5am and 5pm, but showed that mood deteriorated the longer the interns were awake.
‘The field of psychiatry has known that sleep and circadian rhythm play an important role in mental health,’ said Dr Shapiro. ‘However, these findings have only been shown in small samples and in artificial laboratory settings. This study generalises these findings to everyday life across a large number of participants.’
The team did note that individuals’ mood variation is complex and influenced by numerous factors, and that few of the participants stayed awake for more than 18 hours a day.
However, they also highlighted how effective wearable, noninvasive tools such as Fitbits can be for research.
‘Rather than requiring invasive blood draws or temperature monitoring, we are able to obtain similar data from an everyday Fitbit,’ said Dr Shapiro. ‘This opens the door for mental health clinicians to utilise circadian rhythm metrics in everyday clinical practice.’
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