As daylight-saving time comes to an end on Sunday, evenings will feel even longer and darker. This shift is known to exacerbate feelings of seasonal depression, also known as seasonal affective disorder (SAD), which is often linked with light levels.
While there isn’t comprehensive research specifically on how “falling back” an hour affects those with SAD, a 2017 Danish study found an 11% increase in hospital visits for depression in the 10 days after the fall time change. However, this study didn’t distinguish between SAD and other types of depression.
Generally, the annual time change coincides with the time of year when people with SAD experience symptoms more acutely. Even those without a formal diagnosis of SAD or depression often report feeling “a little more blue” during this time. According to experts in mood disorders and sleep medicine, this is likely due to the decrease in daylight hours inherent in the seasonal shift, separate from daylight-saving time.
Dr. Kristin Raj, co-chief of Stanford’s mood disorders clinic, explains that people with SAD are starting to be affected by the decrease in daylight hours. However, it’s difficult to determine whether the shift back to standard time helps or worsens SAD overall. On one hand, there is more light in the morning, which is thought to be beneficial for some individuals. On the other hand, the earlier darkness may make people feel less motivated to engage in activities, potentially worsening their symptoms as physical movement helps boost serotonin and combat depression.
Dr. Kin Yuen, a UCSF sleep medicine specialist, emphasizes that the effects of the time change on depression with seasonality depend on which part of the day is being considered. It’s not entirely clear why light affects mood, but it’s likely linked to the impact it has on the body’s circadian rhythm, the internal clock that operates on a 24-hour cycle.
Exposure to morning light, as opposed to afternoon or evening light, can help individuals with SAD. While the exact reason for this is unclear, it may be related to the body’s natural production of melatonin, the hormone that signals the body to sleep. Melatonin levels peak in the evening, so receiving light 10 to 12 hours after this peak helps shift the circadian rhythm and promotes wakefulness in the morning.
For those with SAD or those who struggle with adjusting to the time change, getting exposure to natural light or using artificial light therapy can be beneficial. Taking a 10 to 20 minute outdoor walk in the morning or using bright light therapy with a minimum intensity of 10,000 lux has been shown to help people acclimate.
Another option is dawn simulation light therapy, which involves using lights that gradually brighten before normal wake-up time. This therapy helps reset circadian rhythms and boost mood.
To conclude, as the clocks turn back, it’s important for individuals with SAD and those who have difficulty adjusting to the time change to prioritize exposure to light in the morning. Whether through outdoor walks, bright light therapy, or dawn simulation therapy, these interventions can help mitigate the effects of seasonal depression.
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