Aging, Sleep, Light and Bad Vision

August 20, 2008

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Something that I had not thought about before is that some of those with certain types of bad vision may have problems with sleeping. This is likely to become more of a problem as the population ages. A lack of perception of light may have a negative effect on setting their biological clock and sleep/wake cycles.

It has long been known that we use light to set our biological clocks and keep us on a regular daily cycle. For instance experiments have been conducted with people who were in rooms with no windows and so we not aware of the whether it was light or dark outside and did not know the time. They only had artificial light that they controlled. Under these circumstances, people do not have a 24 hour day, some have longer days, some shorter. Their clocks were not reset to a 24 hour cycle by the input of daylight.

A regular cycle of light and dark also controls our sleeping patterns. Those who do shift work have confused body clocks and often have trouble sleeping. We seem to be programmed to sleep when it is dark and awake when it is light. Having to sleep when it is light and be alert when it is dark is hard for many people.

It had not occurred to me before, that those whose who have bad vision, may not get sufficient light input to keep their biological clock on a 24 hour cycle. One consequence is that many with bad vision have sleep problems, particularly if previously they had good vision.

With the population aging and more and more people living longer, there are going to be increasing number of people who have a significant age-related decline in vision. For some this decline results in much less light entering the eye, which will affect both resetting the biological clock and controlling sleep patterns.

There are many researchers trying to find the signaling pathways in the eye and brain that connect light to control of the daily cycle and to control of sleep. Recent research has found that “knocking out” a pigment and a recycling protein in the eye in mice causes them to switch from being awake at night, to awake during the day.

This and similar research may provide information about how to mimic the effect of light on the eye. Perhaps in the future there may be eye drops of something similar that will reset the biological clock and help with nromal sleep patterns.

The majority of elderly have problems sleeping or some form of sleep disturbance. Perhaps in the near future, many of them will be helped by artificially resetting the clock. Of course the advice to try to go outside and get some bright light will be helpful to many until then.