Transitioning from daylight saving time (DST) to standard time (ST) is associated with an increase in sleep disorder symptoms, according to the findings of a cross-sectional study published in the journal Neurology.
Circadian rhythm is influenced, in part, by Zeitgebers such as light exposure. People can experience circadian misalignment when exogenous factors do not align with endogenous circadian rhythms, such as body temperature and hormone and melatonin release. This misalignment can occur due to jet lag, working at night, and during the DST/ST or ST/DST transitions.
To evaluate the effect of the time transitions on sleep, researchers sourced data from the Canadian Longitudinal Study of Aging (CLSA), which was a nationwide study conducted between 2011 and 2015. Participants (N=30,097) aged 45-85 years responded to questionnaires about sleep satisfaction, sleep characteristics, and sleep-onset and maintenance disorders. Sleep characteristics were evaluated on the basis of the season in which each individual was interviewed.
The participants were interviewed in the winter (n=7,104), spring (n=9,278), summer (n=6,831), and fall (n=6,884).
[T]here may be small seasonal variations in sleep duration, without any difference in insomnia or somnolence prevalence.
The season groups were:
- mean age, 62.6-63.3 years (P =.002);
- 46.0%-51.6% were men (P <.001);
- 66.9%-69.6% were married or living with a partner (P =.005);
- 43.6%-46.3% were completely retired (P =.001);
- 16.0%-17.4% had depression; and
- 8.4%-9.0% anxiety.
No seasonal differences were observed for the proportion of individuals who reported dissatisfaction with sleep, difficulty initiating sleep, difficulty maintain sleep, or difficulty staying awake. However, individuals interviewed in the summer (mean, 6.76 h) and fall (mean, 6.79 h) reported a shorter duration of sleep (P = .006) than those interviewed in the winter (mean, 6.84 h) or spring (mean, 6.81 h).
Among only the subset of individuals interviewed 1-week before the transition to DST (n=695) or 1-week after the transition to DST (n=738), those interviewed after the transition were more likely to report a shorter sleep duration (adjusted difference, -0.14; 95% CI, -0.27 to 0.00 h).
Among those interviewed 1-week before the transition to ST (n=588) or 1-week after the transition to ST (n=573), those interviewed after the transition were more likely to report:
- sleep-onset insomnia disorder (adjusted odds ratio [aOR], 2.26; 95% CI, 1.19-4.27);
- hypersomnolence with adequate sleep (aOR, 2.08; 95% CI, 1.14-3.79);
- sleep-maintenance insomnia disorder (aOR, 1.64; 95% CI, 1.02-2.66); and
- sleep dissatisfaction (aOR, 1.34; 95% CI, 1.02-1.76).
These trends were no longer observed among individuals interviewed 2 weeks after the ST transition.
The limitations of this study included self-reported outcomes and its cross-sectional design, which did not allow for causal inferences to be made.
The researchers concluded, “Our findings suggest there may be small seasonal variations in sleep duration, without any difference in insomnia or somnolence prevalence. Second, the transition from DST to ST is associated with a transient increase in self-reported sleep disruption.”
Disclosures: Some study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of disclosures.