1.The circadian clock is
-a special mechanic clock.
-a daily cycle of activity observed in many living organisms.
2.Circadian rhythms
-are controlled by the clock.
-are controlled by the brain.
3.Today people can
-brighten the darkness.
-control their inner clock with medicines.
4.City residents can't see stars
-because of the air pollution.
-because the night lights are too bright.
5.Light pollution
-influences human health.
-is not a real problem.
6.Artificial light
-is very hazardous for human eyesight.
-doesn't hurt our sight.
7.Sunlight
-damages our eyes because of the UV.
-is less harmful than artificial light.
8.Melatonin is
-a hormone.
-a medicine for insomnia.
9.Staying awake at night
-is safe when you use enough light.
-influences our natural inner rhythms.