Every day, more and more people appear to suffer from sleep deprivation. This has become a big issue in today’s society. There are many causes — some can be avoided, and some can’t.

According to Better Health, smartphones and other electronics that are used around a person’s bedtime reduces the sleep that a person receives. According to The Sleep Health Foundation, teens who put down their phone an hour before going to be bed can gain up to 21 extra minutes of sleep a night, which adds up to an hour and 45 minutes over a school week.

Too much light exposure can be a big factor as well. Light tells the brain to stay awake. Afternoons that consist of overuse of electronics such as lights from television, mobile phones, and computers can reduce or prevent sufficient production of melatonin, the brain’s chemical neurotransmitter that is responsible for sleep, according to the website Health and Care.

Other things that cause teens to be deprived of sleep are school schedules, homework, and after-school activities (sports, hobbies, part-time jobs, etc.). Other causes are less academic and more socially based. These are the avoidable factors.

Some causes are unavoidable. Puberty hormones “shift” a teenager’s body clock about one or two hours forward, making them sleepier one to two hours later. Teenagers fall asleep later yet some early school start times don’t permit them to sleep in. This routine leads to chronic sleep deprivation, according to Better Health.

Various sleep disorders also rob people of sleep. Insomnia is caused by high levels of stress, leading to anxiety and depression. Sleep apnea is a disorder in which breathing repeatedly stops and starts throughout the night. Restless legs syndrome is an irresistible and constant urge to move the legs. Narcolepsy is a sleep disorder that causes daytime drowsiness. Night terrors are significant feelings of fear and sudden waking. These and other disorders lead to a vicious cycle. When someone gets insufficient sleep, their brain becomes more active. An over aroused brain is less capable of falling asleep, according to Better Health.

According to Psychology Today, sleep deprivation can noticeably affect people’s performance, including their ability to think clearly, react, and form memories. Sleep deprivation also affects mood, which leads to irritability; problems with relationships, especially for children and teenagers; and depression. Sleep deprivation can also increase anxiety.

These factors lead to effects on a person’s daily life. Sleep is important for a person’s overall health, and a bad sleep cycle is associated with numerous health problems. Research shows that not getting enough sleep, or getting poor-quality sleep, increases the risk of high blood pressure, heart disease, obesity, and diabetes. Study after study has revealed that people who sleep poorly are at greater risk for a number of diseases and health problems. And now there are studies conducted to discover why this occurs.

Sleep deprivation can also be very dangerous. Sleep-deprived people who were tested using a driving simulator or performing hand-eye coordination tasks did as badly as, or worse than, people who were intoxicated, according to the National Institutes of Health. Drowsy driving causes thousands of car crashes each year, some of them fatal.

In the short term, a lack of adequate sleep can affect judgment, mood, ability to learn and retain information, and may increase the risk of serious accidents and injury. In the long term, chronic sleep deprivation may lead to a host of health problems, including obesity, diabetes, cardiovascular disease, and even early death.