medwireNews: Poor sleep increases women's risk for depression by reducing their experience of positive affect in daily life, thereby leading to increased negative reactivity, Dutch researchers believe.
"The subtle, repetitive impact of sleep on affect on a daily basis, rather than the subtle repetitive impact of affect on sleep, may be one of the factors on the pathway to depression in women," write Jessica de Wild-Hartmann (Maastricht University, the Netherlands) and colleagues.
Their study, which appears in the British Journal of Psychiatry, involved 553 women who were monitored for sleep and affect for 5 days using the experience sampling method (an ambulatory diary technique). The 471 participants who were free of depression at baseline were then periodically assessed for depressive symptomatology over a mean follow up of 432 days.
The researchers found significant positive correlations between sleep quality (rated on a 7-point Likert scale), sleep period (ie, time spent asleep) and positive affect. They also found significant negative correlations between number of awakenings, sleep latency (ie, time taken to fall asleep) and positive affect.
Additionally, there was a significant negative correlation between sleep quality and negative affect, while increased sleep latency was significantly associated with increased negative affect. Sleep quality was also negatively associated with prior daytime positive affect.
In the longitudinal analysis, all sleep variables (with the exception of sleep latency) were significantly associated with the appearance of depressive symptoms at follow up, although they did not predict the risk for a diagnosis of major depression.
The researchers conclude that there is a close association between subjective sleep and affect in a female population-based sample, both at the micro-level of daily associations as well as at the macro-level of longitudinal associations.
They write: "Based on the data at hand, it can be argued that sleep disturbances may reduce the experience of positive affect in daily life, leading to an increased negative reactivity and enhanced probability of developing depression in the longer term.
"However, more research is needed to unravel the precise mechanisms by which sleep may affect the regulation of affect."
medwireNews (www.medwirenews.com) is an independent clinical news service provided by Springer Healthcare Limited. © Springer Healthcare Ltd; 2013
By Joanna Lyford, Senior medwireNews Reporter