Light During SLeep Affects 'Body Clock'

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January 02, 2008 | 37,784 views

Researchers say sudden exposure to light can upset a sleeping individual's 'body clock,' even if snoozing continues uninterrupted. The experts believe their insights into light's effects on the sleep/wake cycle could further research into the treatment of common sleep disorders.

Nighttime exposure to light begins to motion a chemical process which can function as a precise, selective, and very rapid neural switch controlling the sleep/wake cycle.

The sleep/wake cycle is controlled, in large part, by the secretion of melatonin by the pineal gland, which is located deep within the brain. Melatonin production surges during nighttime sleep. One of the biochemical machines involved in the production of melatonin is this enzyme, AA-NAT (N-acetyltransferase).

It's the only one of the machines there that can turn production on and off. A rise in AA-NAT levels triggers a concurrent rise in sleep-inducing melatonin. AA-NAT levels can be reduced when consumed by barrel-shaped cell structures called proteasomes. Usually, the regular nighttime activity of the pineal gland effectively shields AA-NAT against proteasomal destruction.

The simple clicking on of a bedside lamp means light comes along, blocks (pineal) stimulation, and the (AA-NAT) protein is zapped by the ever-ready proteasomes. The result? A simultaneous drop in melatonin levels. Light exposure is a very good way of controlling melatonin production. Since melatonin is directly linked to the workings of the mind's sleep/wake 'clock,' therapies that replicate the potent effects of light on melatonin production could prove effective in treating conditions such as jet lag or insomnia.

Science, (1998;279:1358-1360)

Dr. Mercola's Comment:

One need to be very careful about light during sleep. This is a great study but I am convinced that the author does not realize the full implications that it has. A very practical one is that it will be very important to not have any light shine on you while you are sleeping. If you are married it would be wise to implement this with your family.

Turning on a light while your spouse, children or other family members are asleep will clearly impair their sleep. Please avoid doing this. Personaly, if you have to get up to empty your bladder or for any other reason, it will be wise to not turn on any lights for the same reason.