When life gets hectic and stressful, our daily routines can be the first thing to fall by the wayside -- early bedtimes become late nights and instead of sitting down for healthy home-cooked meals we may find ourselves grazing on high-calorie, sugar-laden snacks.
Daily routines around eating and sleeping may be more important than we realize in maintaining manageable stress levels and good mental health.
According to a new study from Canadian and French psychologists, regular mealtimes and an early bedtime could ward off mental illness. The researchers propose that this has to do with the way that our body's natural cycles affect certain chemicals in the brain.
Our daily rhythms of sleep and waking are governed by the body's internal "circadian clock," a 24-hour timer that dictates patterns of rest and activity. Daily activity is also influenced by something known as ultradian rhythms, which follow four-hour cycles and are repeated throughout the 24-hour circadian day. These rhythms, which are superimposed over the circadian rhythm, are linked with functions like bodily temperature, feeding, serum hormones and physical movement. Ultradian rhythms may be the reason why humans tend to each three meals daily, spread relatively evenly throughout the day, the researchers note.
The four-hour ultradian rhythms are known to be activated by the brain chemical dopamine, a neurotransmitter associated with pleasure and reward. When dopamine levels are imbalanced in the brain, which can occur in individuals with bipolar disorder and schizophrenia, the typically four-hour cycles can stretch on for as long as 48 hours.
Sleep abnormalities have been thought to be associated with circadian rhythm disruption. But in a new experiment conducted on mice, the researchers showed that these abnormalities result from the imbalance of an ultradian rhythm generator, which operates based on dopamine signaling.
The findings are the first to suggest that there is a dopamine-based rhythm generator in the brain, and that it is related to mental illness. Specifically, when this generator malfunctions, sleep disruption and mania may be induced in bipolar patients, and may be associated with schizophrenic episodes. The researchers note that the findings could have important implications for the treatment of these disorders, and that managing eating and sleeping cycles may play a role in preventing bipolar and schizophrenic episodes.
It's not the first research to suggest a link between bed times and mental health outcomes. A study published in the journal Cognitive Therapy and Research in December found an association between a late bedtime and persistent worry and negative thinking, and a 2013 study correlated a late bedtime with depressive symptoms among shift workers.
The findings were published online in the journal eLife.