We need to get plenty of sleep and turn lights off early enough so as not to throw off our master clock, our suprachiasmatic nuclei, in the brain. When we do not get enough sleep, we seriously impair our ability to learn and remember — and seriously impair our ability to fight diseases and prevent cancer. (Getting enough sleep is also very important when engaging in intense physical activity like a school sport. There is a reason professional athletes get 10-12 hours of sleep a night.)
In Sleep and Technology Don’t Mix: Why You Need to Set an Electronic Curfew, Dr. Mercola writes:
Melatonin is a regulator of your sleep cycle, and when it is suppressed, there is less stimulation to promote sleepiness at a healthy bedtime.
One 2011 study compared daily melatonin profiles in individuals living in room light (<200 lux) vs. dim light (<3 lux).3 Results showed that, compared with dim light, exposure to room light before bedtime suppressed melatonin in 99 percent of individuals, and shortened the time period when the body has an elevated melatonin level by about 90 minutes.
Even the light from your computer screen or smartphone is enough to interfere with your circadian rhythm and melatonin production.
[I]nterrupted or impaired sleep can:
• Dramatically weaken your immune system
• Accelerate tumor growth—tumors grow two to three times faster in laboratory animals with severe sleep dysfunctions, primarily due to disrupted melatonin production. Melatonin inhibits the proliferation of a wide range of cancer cell types, as well as triggering cancer cell apoptosis (self-destruction). The hormone also interferes with the new blood supply tumors require for their rapid growth (angiogenesis)
• Cause a pre-diabetic state, making you feel hungry even if you’ve already eaten, which can wreak havoc on your weight
• Seriously impair your memory; even a single night of poor sleep—meaning sleeping only 4 to 6 hours—can impact your ability to think clearly the next day. It’s also known to decrease your problem solving ability
Copyright 1997- 2014 Dr. Joseph Mercola. All Rights Reserved.
So make sure you get enough sleep most every night. Some nights, yes, you might not be able to achieve the optimum. Emergencies and deadlines cannot be ignored; they do not wait for us. And you want to get plenty of sleep the week of the SAT/ACT, not merely the night before. One night is far from sufficient to catch up on a sleep deficiency.