The science behind our body clock

Hi everyone, this week’s post is about something we talk about a lot – our body clock. Even though everyone’s heard of it, I’m guessing it’s not something people are too familiar with, so I’ll try and explain it here.

The 24 hour cycle we live in accordance with is known as a Circadian Rhythm. This is set according to our environments – in particular in response to the amount of light or darkness. Therefore, the eyes are really important in regulating our circadian rhythms – people tend to forget that our eyes have functions other than sight!

The signals from the retina on the back of the eyeball travel towards the brain via ganglion cells – specialised cells which carry signals containing the visual output. These ganglion cells project towards a structure called the Suprachiasmatic Nucleus (which is fortunately abbreviated to SCN!) in the hypothalmus, which is shown in the image below:

circadian_rhythm_labeled1

The SCN is known as the body’s ‘master clock’, and is responsible for keeping us in time with the circadian rhythm. Studies have shown that if this structure is damaged, then people’s circadian rhythms are virtually abolished. Cohen & Albers (1991) carried out a case study of a 34 year old woman who had part of her hypothalamus taken out as part of an operation to remove a brain tumour. Although the surgery successfully removed the tumour, she was left with a condition called hypersomnolence, which is basically excessive sleepiness in which patients can fall asleep at any time, although the extra sleep does not help reduce the symptoms. This shows the importance of the SCN in regulating our sleep pattern, and how disorientated we would be without it.

I hope you found this post interesting – check back next Thursday for my next blog post all about sleep.

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