Why do we sleep?

There are many theories about why we sleep and dream, and many of these involve memory in some way (including Freud’s theory of why we dream). A relatively recent theory has been gathering support, variously called synaptic renormalisation hypothesis or synaptic homeostasis hypothesis (aka ‘SHY’ – first proposed by Tononi and Corelli, 2003). The basic […]

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Shift work and heart attack

In our A2 Complete Companion we reported a study by Knutsson et al. (1986) who found that shift workers were three times more likely to develop heart disease than non-shift workers. A study just published by Hackam et al. ( 2012 ) confirms this, claiming a 24% increased risk of a coronary event and 5% increased risk of stroke. […]

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Link between insomnia and narcolepsy

Henry Nicholls is a science writer and narcoleptic, a condition characterised by a frequent and overwhelming need to sleep. The current thinking is that narcolepsy develops in genetically vulnerable individuals when the immune system mishandles an infection.The outcome is an autoimmune attack on a region of the hypothalamus that produces the hormone orexin (aka hypocretin). […]

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SAD, melatonin and serotonin

Juliette Massey-Smith wrote in the following query: I was wondering if you could help… I was re-reading about SAD in your AQA textbook and read on p.4 that in winter melatonin and serotonin are higher and this causes depression, but then also that LACK of serotonin causes it… What am I missing? This error was corrected […]

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Blue light bad

Early temporal isolation studies overlooked the fact that artificial light has an effect on circadian rhythms but more recent research showed that even fairly dim lighting may reset the SCN (suprachiasmatic nucleus). Even more recently research has found that blue light is particularly effective – for good and bad. The story starts with blind people […]

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