Poor sleep increases desire to eat

The impact of sleep deprivation on food desire in the human brain.
Stephanie Greer, Andrea Goldstein and Matthew Walker.
Nature Communications, August 6, 2013

Epidemiological evidence supports a link between sleep loss and obesity. However, the detrimental impact of sleep deprivation on central brain mechanisms governing appetitive food desire remains unknown. Here we report that sleep deprivation significantly decreases activity in appetitive evaluation regions within the human frontal cortex and insular cortex during food desirability choices, combined with a converse amplification of activity within the amygdala. Moreover, this bi-directional change in the profile of brain activity is further associated with a significant increase in the desire for weight-gain promoting high-calorie foods following sleep deprivation, the extent of which is predicted by the subjective severity of sleep loss across participants. These findings provide an explanatory brain mechanism by which insufficient sleep may lead to the development/maintenance of obesity through diminished activity in higher-order cortical evaluation regions, combined with excess subcortical limbic responsivity, resulting in the selection of foods most capable of triggering weight-gain.

Emotions are at the center of our thinking

Think, blink or sleep on it?

Think, blink or sleep on it? The impact of modes of thought on complex decision making.
Q J Exp Psychol (Colchester). 2009 Apr;62(4):707-32. Epub 2008 Aug 23.
Newell BR, Wong KY, Cheung JC, Rakow T.

This paper examines controversial claims about the merit of "unconscious thought" for making complex decisions. In four experiments, participants were presented with complex decisions and were asked to choose the best option immediately, after a period of conscious deliberation, or after a period of distraction (said to encourage "unconscious thought processes"). In all experiments the majority of participants chose the option predicted by their own subjective attribute weighting scores, regardless of the mode of thought employed. There was little evidence for the superiority of choices made "unconsciously", but some evidence that conscious deliberation can lead to better choices. The final experiment suggested that the task is best conceptualized as one involving "online judgement" rather than one in which decisions are made after periods of deliberation or distraction. The results suggest that we should be cautious in accepting the advice to "stop thinking" about complex decisions.

How Sleep affects Memory and Congition

Functional neuroimaging insights into how sleep and sleep deprivation affect memory and cognition.
Chee Michael WL and Chuah Lisa YM b
Current Opinion in Neurology. 24(4):417-423, August 2008.

Purpose of review: The review summarizes current knowledge about what fMRI has revealed regarding the neurobehavioral correlates of sleep deprivation and sleep-dependent memory consolidation.

Recent findings: Functional imaging studies of sleep deprivation have characterized its effects on a number of cognitive domains, the best studied of these being working memory. There is a growing appreciation that it is important to consider inter individual differences in vulnerability to sleep deprivation, task and task difficulty when interpreting imaging results. Our understanding of the role of sleep and the dynamic evolution of offline memory consolidation has benefited greatly from human imaging studies. Both hippocampal-dependent and hippocampal-independent memory systems have been studied.

Summary: Functional imaging studies contrasting sleep-deprived and well-rested brains provide substantial evidence that sleep is highly important for optimal cognitive function and learning. The experimental paradigms developed to date merit evaluation in clinical settings to determine the impact of sleep disruption in sleep disorders.

Think positive

Neural mechanisms mediating optimism bias.
Sharot T, Riccardi AM, Raio CM, Phelps EA.
Nature. 2007 Nov 1;450(7166):102-5

Background: Humans expect positive events in the future even when there is no evidence to support such expectations. For example, people expect to live longer and be healthier than average, they underestimate their likelihood of getting a divorce, and overestimate their prospects for success on the job market.

Methods: We examined how the brain generates this pervasive optimism bias. Here we report that this tendency was related specifically to enhanced activation in the amygdala and in the rostral anterior cingulate cortex when imagining positive future events relative to negative ones, suggesting a key role for areas involved in monitoring emotional salience in mediating the optimism bias.

Results: These are the same regions that show irregularities in depression, which has been related to pessimism. Across individuals, activity in the rostral anterior cingulate cortex was correlated with trait optimism.

Conclusion: The current study highlights how the brain may generate the tendency to engage in the projection of positive future events, suggesting that the effective integration and regulation of emotional and autobiographical information supports the projection of positive future events in healthy individuals, and is related to optimism.