If you don't get into deeper phases of sleep your body cannot repair itself. Cells don't rejuvenate. Sleep is necessary for this repair process to occur.  Electromagnetic radiation inhibits the production of a hormone melatonin. Melatonin is secreted by the pineal gland in the brain and is produced about 90minutes after falling asleep. Thus, melatonin levels rise at night and remain low during the day. Melatonin has many useful effects but the most common is that of regulating the sleep cycle. When cell phone radiation ,or other EMR, inhibits this important hormone the sleep cycle is compromised. This is the main reason why people today have insomnia.