We all know that feeling of waking up in the morning. It’s completely dark outside and all you want to do is go back to sleep. Then it dawns on you. It’s Monday morning and you have to go to school. You went to bed way too late last night, again.

A recent study has shown that teenagers nowadays don’t get enough sleep at night and go to school tired. Some scientists believe the cause behind this is biological, whereas other experts claim that teenagers stay up so late because of distractions. Furthermore, early high school starting times could also contribute to tiredness among teens.

Research shows that the average amount of sleep that teenagers get is between 7 to 7.5 hours. However, they really need between 9 and 9.5 hours, compared to the eight hours needed for adults. A recent study at Drexel University of students from ages 12-18 found that 20 percent of those studied got the recommended eight or more hours of sleep. This means that the other 80 percent of the students in the survey did not get enough sleep. Another study of Rhode Island teenagers showed that 85 percent were sleep-deprived. Forty percent went to bed after 11 pm and 26 percent said they got less than 6.5 hours of sleep on school nights. As can be seen from this research, sleep deprivation among teenagers are increasing significantly across the world.

So, what are the reasons for teens not getting enough sleep? Some experts argue that technology plays an important role. It makes it very difficult for teens to be able to put away their phones and go to bed when there is always something exciting happening, like somebody texting them, a good TV show or something happening on social media. Furthermore, the blue and white bright lights from the screens of our phones and laptops are very similar to daylight, hence tricking your body that it’s day when you’re actually supposed to sleep. Mariana Figueiro of the Lighting Research Center at Rensselaer Polytechnic Institute and her team showed that two hours of iPad use with maximum brightness was enough to suppress people’s normal nighttime release of melatonin. Melatonin is a hormone that tells your body it is night and helps you get sleepy. If you delay that signal, Figuero claims that you can delay sleep.

Studying and homework could also be another reason why teens stay up so late. A poll of public school teachers has found that on average, high school students have 3.5 hours of homework every day and in total 17 hours every week. However, this varies from school to school but could be another reason why teenagers stay up – they have too much homework.

On the other hand, some experts believe that the hormonal and biological changes in teens affect their ability to sleep. A recent study has shown that the melatonin levels rise later at night for teens than they do in children and adults. Hence, puberty affects your biological clock and makes it easier for teenagers to stay up at night and then be more tired in the morning.

Because the average teenager gets too little sleep, this also affects their ability to function in school. It has been shown that sleep deprivation can affect your mood, performance, attention, learning, behavior and biological functions. Teenagers who don’t get enough sleep also have troubles concentrating and paying attention in class, hence receiving worse grades. Sleep deprivation and disruption also increase the level of the stress hormone cortisol. In other words, it makes students more stressed, however less capable and organized to do their work.

Moreover, another reason why teenagers may be so tired in school is because of early hours. It exhausts the teenager to stay up so late at night, whether it’s because of homework, technology or hormones and then having to wake up so early the next morning. According to Dr. Sujay Kansagra, early school start times force students to start classes when their brain is practically still asleep. For example, seven high schools in Minneapolis wanted to see if starting school later would benefit their students, and decided to move their start times from 7:25 am to 8:30 am. As a result of the change, the teens got approximately five more hours of sleep per week, attendance rates went up and student-reported depression went down. It has also been proven that teenagers that get enough sleep have a reduced risk of being overweight, suffering depression and less likely to be involved in automobile accidents. On the other hand, they also receive better grades and have improved social skills.

So what can be changed? Firstly, it’s important to understand the effect of screens on sleep. While there is nothing wrong to be on your phone before sleep, one could change the setting on their devices from bright blue light to yellow, which stimulates your brain and makes it easier for you to fall asleep due to the natural light. Secondly, it’s also important to reduce stress. As seen above, later yet reasonable school hours had a positive impact on students. Exercise or healthy activities outside of school, as well as eating healthier food can also have a positive impact. Hence, instead of blaming teenagers for being tired, lazy and falling asleep in class, it’s time to educate both teenagers and adults, and focus on what needs and can be done in order to help improve the situation.