Our body’s internal clock is linked to the sun, which is why we’re naturally programmed to sleep at night and be active during the day. We’ve known for some time that exposure to light at night can alter our biorhythms and the normal fluctuations of melatonin, the neurotransmitter that governs the sleep/wake cycle.
A large study from the UK published in May 2018 has associated disruption of body clocks with major depression, bipolar disorder, loneliness, mood swings, lower levels of happiness and satisfaction with health. Although the investigation did not establish cause and effect, it did find a strong association between mental health problems and a body clock that is out of sync. (There is also the chance, however, that mental health conditions can disrupt the body clock, not the other way around.)
Researchers from Scotland, Ireland and Sweden gathered health information from some 500,000 British adults and asked 91,105 of them between the ages of 37 and 73 to wear accelerometers on their wrists continuously for one week in order to track all their movements. They excluded participants who reported having insomnia or sleep apnea. Those who wore the accelerometers were asked later to respond to mental health questionnaires.
After controlling for factors such as age, sex, the season during which an individual wore the accelerometer, socioeconomic and smoking status and history of childhood trauma, the researchers concluded that the participants who were very active at night and inactive during the day were “disrupted.” They found that between six and 10 percent of those in this group were more likely to have been diagnosed with a mood disorder than were study participants whose routines adhered more closely to a more typical sleep/wake cycle. Moreover, the data showed that participants whose sleep/wake cycles were disrupted tended to be male, overweight or obese, have lower education levels and more likely to have experienced childhood trauma.
To keep your body clock in sync, lead investigator Daniel Smith, a professor of psychiatry at the University of Glasgow, recommends avoiding activities after about 10 p.m. that could disrupt circadian rhythm, including the use of cell phones. He noted that study participants most likely to have problems were those who were on their cell phones at midnight, checking Facebook, and those who got up in the middle of the night to make a cup of tea.
The study’s limitations include the fact that activity was tracked for only one week and not at the time participants were asked to respond to the questionnaires. The age of the participants is also an issue, since mental health disorders tend to develop at relatively young ages.
We know that using cell phones, tablets and computers prior to sleep can lower levels of melatonin. To improve the quality of your sleep, I have emphasized elsewhere on this site the importance of turning off technology one to two hours prior to bedtime. Learn more about natural sleep aids here.
Andrew Weil, M.D.
Daniel Smith et al, “Association of disrupted circadian rhythmicity with mood disorders, subjective wellbeing, and cognitive function: a cross-sectional study of 91 105 participants from the UK Biobank.” The Lancet Psychiatry, May 15, 2018, DOI: doi.org/10.1016/S2215-0366(18)30139-1