Dark nights could be better for our health

It could be time to get heavier curtains in your bedroom. A new study has added to the growing evidence that sleeping in absolute darkness is beneficial – in fact vital to our health.

It all seems to have something to do with the production of melatonin – the hormone  present in plants, animals and humans where it is released during the night to establish circadian rhythms.

In a paper published today, scientists say they have found that melatonin helps combat obesity and diabetes in rats. The study, published in the Journal of Pineal Research, confirms similar studies conducted by these researchers during the past three years.

They believe the benefits come from improved consumption of oxygen, the reduction of free-radicals and protection of the mitochondrial membrane.

The problem is, however, that the natural process of producing melatonin is interrupted by the exposure of artificial lighting during the night, which reduces the levels of endogenous melatonine—for instance, many people are in the habit of sleeping with their lamps, TVs or their computers switched on, or with the blinds drawn up.

“For all these reasons, it is important to try to sleep in absolute darkness, to avoid interference in the generation of melatonin,” says professor Ahmad Agil of the University of Granada, who led the study.

This appears to support other research.

In August, Cosmos reported on another study that suggested that greater production of melatonin improved the performance of breast cancer drug tamoxifen. That research compared the growth of breast cancer in rats kept in darkness overnight with rats given nightlights.

The cancers in rats given pitch-dark nights grew more slowly and tamoxifen dramatically shrank their tumours.