Running out of time: Ageing and the biological clock.
There are age related changes in the activity of the internal biological clock. Changes are evident in the actual cells that make up the clock, as well as within input pathways. We show that in middle aged animals, simply altering the characteristics of incoming environmental signals is enough to improve clock function. However, in animals of very advanced age this is not possible. As disruption of clock function becomes increasingly pronounced, we see that this seems to be at least in part mediated at the level of the pacemaker cells via altered sensitivity of the NMDA receptor. Further, in these oldest animals we have found that synchronisation can be improved when they are pretreated with growth factors. Difficulty sleeping is one of the main reasons why people over the age of 65 visit their GP. The duration, timing, and value of sleep is controlled by an internal body clock. Our work raises the possibility that in the initial stages of age related clock changes, simple changes in light levels could help older individuals to improve sleep quality. It is hoped that this could lead to improved recommendations to improve circadian clock function in the aged.