Effect of daylight saving time on lighting energy use: A literature review

The principal reason for introducing (and extending) daylight saving time (DST) was, and still is, projected energy savings, particularly for electric lighting. This paper presents a literature review concerning the effects of DST on energy use. Simple estimates suggest a reduction in national electricity use of around 0.5%, as a result of residential lighting reduction. Several studies have demonstrated effects of this size based on more complex simulations or on measured data. However, there are just as many studies that suggest no effect, and some studies suggest overall energy penalties, particularly if gasoline consumption is accounted for. There is general consensus that DST does contribute to an evening reduction in peak demand for electricity, though this may be offset by an increase in the morning. Nevertheless, the basic patterns of energy use, and the energy efficiency of buildings and equipment have changed since many of these studies were conducted. Therefore, we recommend that future energy policy decisions regarding changes to DST be preceded by high-quality research based on detailed analysis of prevailing energy use, and behaviours and systems that affect energy use. This would be timely, given the extension to DST underway in North America in 2007.     

Entrapment and perceived status in graduate students experiencing a recurrence of major depression.

The present study used a prospective design to test the role of involuntary subordination as a predictor of major depression. Involuntary subordination is a construct derived from social rank theory and has been implicated as a cause of major depression. Its most salient features include feelings of entrapment and unfavourable social comparisons (i.e., low perceived status). An initial sample of 146 graduate students underwent a diagnostic interview to confirm a history of major depression and also completed measures of entrapment and social comparison. After 16 months, participants were assessed for a recurrence of major depression. Participants who experienced a recurrence of depression had significantly higher levels of involuntary subordination (as measured by factor scores of entrapment and social comparison). A logistic regression analysis also showed that involuntary subordination predicted recurrence of depression, even when controlling for current major depression and the number of previous episodes. The present study demonstrates the advantages of adopting a social rank perspective in modeling major depression. (PsycINFO Database Record (c) 2010 APA, all rights reserved)