At this time of year, many people struggle to get up in the dark mornings. The lack of light on winter mornings affects sleep-related hormones, leaving many tired and unrefreshed.
A new study, published in the October issue of the Journal of Affective Disorders, has assessed individuals with symptoms of delayed-phase sleep phenomenon (DPSP) and has found links with SAD (1). In DPSP, the bodyclock’s natural cycle of sleep and wakefulness is altered, and the effect is similar to jet lag. As a result, those with DPSP have difficulty getting to sleep at night, and struggle with rising in the morning.
In the study, researchers assessed a group of 327 individuals with DPSP, and compared them to a group of 331 controls (individuals without DPSP). They found that those with DPSP were much more likely to have seasonal affective disorder (SAD).
The research also found that those with DPSP were more likely to experience changes in appetite, body weight and fatigue during the darker months – symptoms that are common in SAD.
The study concluded that both DPSP and SAD may have the same underlying cause.
One treatment that has shown positive results with both DPSP and SAD is dawn simulation therapy. Dawn simulators, or sunrise alarm clocks, are alarm clocks that use gradually increasing light to simulate the sunrise each morning. Light receptors in the retina can detect the light, even through closed eyes. This type of light therapy can be used to help ‘reset’ the body clock, making winter mornings less of a struggle.
A recent controlled study found that both light boxes and dawn simulator alarm clocks were effective in treating symptoms of SAD (2), while a recent review recommends light therapy to address DPSP (3). While standard light boxes are indeed useful in this regard, dawn simulators can be more convenient for many. Using a dawn simulator alarm means that you don’t have to set aside time each day for your light therapy. And so for those with DPSP or SAD, using a dawn simulator that works while you sleep may make winter mornings less of a struggle.
Written by Nadia Mason
1. Lee et al (2011) Delayed sleep phase syndrome is related to seasonal affective disorder. Journal of Affective Disorders 133(3):573-579
2. Terman & Terman (2006) Controlled trial of naturalistic dawn simulation and negative air ionization for seasonal affective disorder. Am J Psychiatry 163(12):2126-33.
3. Martinez & Lanz (2011) Circadian rhythm sleep disorders. Indian J Med Res 131: 141-149.
4. Image courtesy of Stuart Miles.