How is your body clock?

There was an interesting interview with Professor Russell Foster from the Circadian Neuroscience Department at the University of Oxford, broadcast on Start the Week on Radio 4 at 9am today – 16th. May 2022.  Professor Foster covered areas of the biology of circadian rhythm and give an explanation of how it works in maintaining our body clocks and the sleep/wake cycle. One of the most interesting comments he made was that it is now established that taking antihypertensive tablets at bedtime can lead to a reduction in the risk of stroke by 50% compared with taking the same tablets after rising in the morning.  If you are taking blood pressure lowering drugs then this is certainly worth considering, but never make changes to your drug therapy without discussing it with your general practitioner.

Our internal body clocks are kept in sync. with the 24 hour cycle of light and darkness that we experience in the world through our eyes. Special receptors in the back of the eye (melanopsin receptors) react to light, and every day adjust the clock when we wake and open our eyes to make sure that it is synchronised with the light and dark cycle of the external environment. This feeds information to the suprachiasmatic nucleus deep in the brain, which ensures that the rest of the tiny clocks that are contained within each cell of our bodies are synchronised and act as one, in the same way that a conductor co-ordinates an orchestra. Thus, if you put a study subject into an environment where the light is neutral and they cannot pick up the cues of day and night, their body clocks are shown to be slightly longer than 24 hours, and gradually sleep will come later and later day by day. This has relevance in situations such as care homes where there may be reduced amounts of natural light. There is evidence that exposure to natural light improves the sleep of people in care homes and may even have a positive effect on dementia, as Professor Foster pointed out.

So the message is to try to maintain good sleep habits with a regular bedtime and rise time, and get plenty of light in the mornings and a nice wind down in dim light before bed. Common sense but worth saying – and now backed up by medical science.