A couple of weeks ago, my brother & I were discussing the topic of sleep. This topic came up because it was around midnight. When I looked outside, I noticed that in some neighbouring houses the lights were still on and this got me thinking. How many people are evening people? So as a science student, I decided to keep track of how many houses had lights turned on between 23:00-24:00 for a whole week. The average was 15.7±2.1 out of 60 houses (26.2%). A quick search learned me that around 25% of the population are night owls, 15% are early birds and the rest are intermediate types. Our sleep cycli are regulated by our biological clock. This is a group of brain cells that produce rhythms of about 24 hours. In response to various factors such as daylight, hormones or genes, this rhythm can be shifted. The impact of this rhythm is quite large. It influences for example our body temperature, our appetite and our blood pressure. The picture below shows the main activities in the body that are regulated by the biological clock.
Variations in genes, but also in lifestyles can determine whether someone is an evening or a morning person. Although everyone has a ‘default mode’ of their sleep/wake rhythm, it can certainly be trained by circumstances like working a night shift or travelling across time zones. The function of sleep is a topic that generates a lot of debate. Over time, many theories were made up in order to explain our need for sleep. Some say that sleeping is meant to restore the body from stressful events ocurring during the day. Others say that we need sleep so that our brain can reorganise connections between the different brain areas. This reorganisation leads to improved learning and memory. So while we seem to be inactive during sleep, parts of the brain are active, which can be seen with EEG. During sleep the brain activity will change and these changes are called sleep states. For more information on these states and what they look like on EEG, you can go to this link: http://healthysleep.med.harvard.edu/healthy/science . There are more fascinating facts on sleep, but I’ll go into that another time. In the mean time, you might be interested in these websites: http://en.wikipedia.org/wiki/Night_owl_(person) http://en.wikipedia.org/wiki/Circadian_rhythm
Comments/questions/suggestions/ideas for other topics are always welcome!