The Impact of Daylight Savings Time
What do you and your patients need to know about adjusting to daylight savings time?
As we get ready to spring forward and lose an hour of sleep, some patients may express concern or worry. This slideshow shares facts and busts myths to help you help your patients.
A survey of more than 55,000 individuals in Europe found that the timing of sleep on “free” days (ie, weekends) followed the seasonal progression of dawn under standard time, but not under DST.1 Investigators also found that adaptation to the change in daylight length was interrupted by the introduction of summertime. In other words, beyond simply losing an hour of sleep, DST causes our circadian system to be out of sync for 8 months of the year. In addition, the impact is more profoundly seen in patients with preexisting circadian rhythms issues and/or melatonin secretion problems.
There has been the suggestion that the DST change may trigger an increase in mood disorder symptoms. This was originally proposed by Harvard researchers based on observations from 5 DST changes over a 2.5-year period.2 A more systematic study that covered 10 years and 20 changes found some years with a pattern of mood disorder symptoms and some years without a consistent pattern.3
However, a large-scale study out of Denmark that looked at 185,419 hospital contacts for unipolar depression found that the transition from summer time to standard time was associated with an 11% increase in the incidence rate of unipolar depressive episodes.4 This effect dissipated over approximately 10 weeks after the time change.
Although these findings are inconclusive when it comes to psychiatric illnesses as a whole, there is strong evidence of a link regarding seasonal affective disorder (SAD). Multiple studies have established that decreased daylight length is clearly associated with an increased incidence of SAD.5,6
Talk with patients and explain that changes brought on by DST could theoretically impact their mood in the same way travelling across time zones holds the potential for disrupting the body clock. This caution should be particularly heightened with patients who have SAD. Suggesting an extra hour of sleep may be helpful, but there is currently little objective evidence in the literature to support this notion.
There is a possibility that light therapy could be used for patients worried about DST effects. Although the use of bright light therapy in the treatment of SAD is well known, multiple studies have also shown that it can be used as an effective treatment for other circadian rhythm-related issues, such as jet lag and shift work disorder. However, its utility in mitigating the effects of DST remains untested and unproven.
There is increasing concern about the effect of melatonin on reproduction, especially regarding its use in children and adolescents. It must be recognized that melatonin is a hormone—no different from insulin or thyroid hormone—and the same amount of caution should be used when prescribing and/or advising patients to take it without proper testing and confirmation of an abnormality. If there is concern regarding delayed or abnormal melatonin secretion, best practices dictate that a Dim-Light Melatonin Onset test (DLMO) be performed prior to initiating melatonin treatment.
To see the original article, visit Psychiatric TimesTM here.
