Bobby found a list of some unhealthy habits that we could all be guilty of without even knowing it. These are all according to science, courtesy of Science 101. Are you guilty of any of these?

1. Don’t sleep with the lights on

Lights at night are a new thing for our bodies, which evolved to sleep when the sun goes down. Before sleeping, your body starts making melatonin, a hormone that helps you sleep. But lights, especially bright or blue-hued lights, can disrupt the production of melatonin in your body, making it harder to fall asleep.

2. Biting your nails could make you sick

Your hands are the dirtiest part of you — they touch everything: doorknobs, food, toilets, other people. The list goes on. Putting these dirty digits in your mouth could give you a cold or another illness, depending on what microbes are chilling on your fingers.

3. Don’t (static) stretch before working out

If you’re warming up before a workout, don’t hold stretches. Pre-workout stretching temporarily weakens your muscle strength, impacting your performance and causing you to run more slowly or lift less effectively. Instead, for a warm-up, you can do high knees, squats, light biking, jumping jacks, arm circles, or another moderate intensity movement.After your workout, you can do those static stretches that you hold for about 30 seconds or so. They might help you become more flexible, but science suggests they have no effect on whether or not you injure yourself while exercising. In fact, science is a little fuzzy on what stretching actually does and if it has any substantial long-term effect.

4. Sitting all day could be harmful to your health

Many of us spend nearly the whole day sitting — between the office (or school), the car, and the couch, there’s little physical activity. Some studies have linked the practice with health concerns like obesity, high blood sugar and blood pressure, death from cardiovascular disease, and even cancer. While sitting for long periods of time hasn’t necessarily been proven to directly cause disease, a sedentary lifestyle does seem to be harmful and may affect your brain as well as your heart. However, exercising regularly appears to reduce the effects. While it’s hard to not sit when you have to work all day, try getting up and moving regularly or work in a standing position.

5. Don’t brush your teeth right after eating

It seems counterintuitive to brush your teeth before breakfast unless you’re in the habit of eating on the way, but it can be the best option. Brushing your teeth right after eating or drinking can be a harmful habit for your tooth enamel, especially if you ate something acidic. Acid isn’t good for the enamel on your teeth; it erodes the protective covering. As a result, brushing right after you eat can push the acid even further into your teeth. Plus, once the acid gets through the enamel, it starts eating at another layer on your teeth: the dentin. Wait at least 30 minutes after eating to brush your teeth.

6. Hitting the snooze button can ruin your mental health

It’s so easy to wake up to your alarm and simply press the snooze button. Those extra few minutes are so enticing. But if you’re already very tired, snoozing is the last thing you need. After snoozing the alarm, you will likely start a new sleep cycle, which will be interrupted once the alarm goes off again.

7. Don’t sleep on your stomach

While we’re on the topic of sleep, you may as well know that sleeping on your stomach is terrible for your neck and back. Since you have to turn your neck to avoid suffocating while sleeping, your upper cervical vertebrae lock into place. This can give you neck problems and headaches.

8. Wearing contacts too long can lead to blindness

When you wear contacts, your eye is deprived of oxygen the entire time you have them in. To deal with this, your cornea grows new blood vessels, which can lead to inflammation and blindness. Usually, your cornea, the clear protective layer of your eye, has no blood vessels.

9. Don’t look at your computer screen for too long

While computers have brought great convenience and excessive amounts of information to our fingertips, they’ve also brought their screens. They aren’t bad except for the fact that we like to spend most of our waking hours looking at them. As a result, people can become plagued by computer vision syndrome.

10. Teeth whitening strips might be stripping proteins out of your teeth

Recently, a scientist bought some teeth off eBay so she could use them for an experiment. No, this isn’t a Twilight Zone episode. She wanted to know how teeth whitening strips affect teeth — other than the supposed whitening. She put some artificial saliva on the teeth and then proceeded to experiment. She found that teeth had fewer proteins in them when they went through more whitening strips. The hydrogen peroxide in the strips was breaking down the protein’s chemical bonds. Your teeth can replenish these proteins in the dentin layer, but not the enamel. So it’s unclear whether or not these strips are doing lasting damage.

11. Don’t leave the toilet open when you flush

Every time you flush your toilet, it sends a toilet plume of poop particles and microorganisms shooting into the air. They can go as high as 15 feet and fall onto the floor, the sink, and your toothbrush. Close the darn toilet lid before you flush the toilet. It’s incredibly nasty.

12. Poor posture has a myriad of impacts on your health

For good posture, you want to have your head, shoulders, and hips aligned (plus knees and feet when standing). While sitting hunched over isn’t necessarily bad, holding any position for too long isn’t good for your body. Even sitting or standing at work all day in perfect posture isn’t great if you never move around.

13. Don’t clean your ears with cotton buds

There’s nothing like the feeling of freshly cleaned ears after a shower, but did you know it isn’t really good for you? Our ears and their wax evolved long before anyone invented Q-tips — which literally say on the box not to put them in your ears. Cotton swabs often push earwax further in and can even damage your eardrum.

14. Sleeping excessively on the weekend

If you’re in a pattern of sleeping little on the weekdays and then sleeping a lot on the weekends, it isn’t a good habit for your health. Lack of sleep is generally a bad thing since it is associated with high blood pressure, heart disease, obesity, diabetes, and other issues, but this pattern is even worse. You might think that sleeping extra on the weekends can make up for your sleep deprivation over the week, but a recent study suggests that it’s actually more harmful. The irregular sleep cycle actually impacts your insulin sensitivity (which is related to diabetes) and your blood sugar regulation. Generally, it’s best to go to sleep and wake up at the same time each day.

15. Don’t go on your smartphone before bed

It sure seems like we have a lot of bad sleeping habits! This one is really hard to kick: don’t use your smartphone before going to bed. The reason is similar to what we’ve already talked about; the screen light interferes with your body’s normal processes. When looking at a screen before bed, your body doesn’t make as much melatonin as it normally would, so it takes you longer to fall asleep. Your sleep quality suffers and you feel worse in the morning. Plus, it screws with your circadian rhythm which is linked to your mood, metabolism, and appetite. So set the screen to a warmer tone at night and put the phone down a little before going to bed.

The original and full article is available on Science 101.