Wednesday, 4 April 2012

Sleep: How much we need and what keeps us awake

Have you ever wondered how we sleep? Being a teenager myself, I rarely think of the implications of a bad sleep but recent studies have indicated that it can really be harmful in the long run. Derk-Jan Dijk and Raphaelle Winskey-Sommerer’s article (New Scientist Magazine, 9th Feb 2012) presents research portraying the differences in sleeping patterns and requirements that is necessary for each individual.

The circadian rhythm and biological clocks are vital parts of humans which allow the body to react to different times of the day. The circadian rhythm consists of series of changes, whether psychological or physical, that follows our daily 24 hour cycle (National Institute of General Medical Sciences, 2012). The circadian rhythm is actually governed by a set of genes. The genes are called “clock genes” which create proteins throughout the day to maintain a 24 hour biological clock. The body’s master clock is called the “suprachiasmatic nucleus” (or SCN) which is located in the hypothalamus of the brain.
The hypothalamus
(http://health.superlogical.net/obesity-the-solution/)
SCN creates a substance called melatonin (Reece et Al., 2012) which causes drowsiness. Lighting is a vital factor in determining sleep patterns and also one’s biological clock. Experiments have uncovered that light from our surroundings can actually stop the creation of melatonin so one does not feel as drowsy. A study in the UK has discovered the problems surrounding the exposure to artificial light and that reducing the intensity of light can greatly decrease sleep disturbance. (Santhi, 2011) It is now known that primary reason light effects sleep is because it stimulates certain cells (called “intrinsically photosensitive retinal ganglion cells”) which is able to “synchronise the biological clock” (Djik, 2012) and cause the body to distinguish between night and day. This just means that we can possibly gain sleepiness by minimising all sorts of artificial light around us, such as turning off the TV or laptop. This idea is important as we can use this every night to get a good sleep.

Effect of light on Circadian Cycle
(http://upload.wikimedia.org/wikipedia/commons/5/55/Circadian_rhythm_labeled.jpg)
New research is showing that lack of proper sleeping patterns can cause diseases. Data now suggests individuals who work late shifts have an increased risk of diabetes as well as cardiovascular diseases due to the disruption of the circadian rhythm and also the biological clock. (Wang, 2011) Disruption of the circadian rhythm can happen by jet lag as the time recognised by the body and the actual time in the new time zone will be different. The clock genes must be further understood as medicines can be eventually be created to counter effects of late night work and jet lag.
We sleep for most of our lives and yet we take it for granted. 

The article highlights the importance of sleeping. With this knowledge that we are learning from studies, the harmful effects of irregular sleeping patters can be treated. Understanding the workings of clock genes can enable the creation of drugs that can treat the unwanted effects of jetlag and late-night shift work.     

References:
Dijk, D, Winskey-Sommerer, R (2012) Sleep: How much we need and what keeps us awake, New Scientist Magazine (http://www.newscientist.com/article/mg21328503.100-sleep-how-much-we-need-and-what-keeps-us-awake.html?full=true) (9th February 2012)

Gooley, J, Chamberlain, K, Smith, K, Khalsa, S, Rajaratnam, S, Reen, E, Zeitzer, J, Czeisler, C, Lockley, S  (2010) Journal of Clinical Endocrinology and Metabolism, vol 96, p E463.
10.1210/jc.2010-2098 http://jcem.endojournals.org/content/96/3/E463 (7th September 2010)

Santhi, N, Thorne, H, Veen, N, Johnsen, S, Mills, S, Hommes, V, Schlangen, L, Archer, S, Dijk, D (2011), Journal of Pineal Research: The spectral composition of evening light and individual differences in the suppression of melatonin and delay of sleep in humans (DOI: 10.1111/j.1600-079X.2011.00970.x)

Reece, Meyers, Urry, Cain, Wasserman, Minorsky, Jackson, Cooke (2012), Campbell Biology, 9th Ed, Pearson Australia Group

Kripke, D, Garfinkel, L, Wingard, D, Klauber, M, Marler, M (2002), Archives of General Psychiatry, vol 59, p 131

Wang, X, Armstrong, M, Cairns, B, Key, T, Travis R (2011), Occupational Medicine, vol 61 pg 78

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