How can I stop having nightmares or how can I have a deeper sleep?

You can get deeper sleep by practicing "sleep hygiene". This involves setting a consistent sleeping and waking time (going to bed and waking at the same times everyday). Our bodies like repetition and getting in a routine like this helps with mood and energy. Stay away from caffeine close to bed time. You might say "I can sleep fine after drinking caffeine". This might be true but the quality of your sleep will not be as deep than if you choose to skip that extra cup of coffee. If you would like more tips like this take a look at the sleep foundation website. https://www.sleepfoundation.org/sleep-topics/sleep-hygiene

Try talking to you doctor see if they have anything to help you with. For a deeper sleep you should try making sure there is no noise when you are sleeping

You cannot control your dreams or nightmares. Deeper sleep can come easy when you're really tired, but not so tired that you can't even fall asleep. Taking a sleep-aid and doing relaxing things before bed can help.

Definitely putting away the computer at night. Doing a late light workout helps me go to sleep as well.

You can try to read a book before sleeping, so that you can keep thinking about it in the few minutes before you fall asleep. Try to get away of horror movies or video or even anything that can impact your thinking with bad memories or violent scenes. You can also think about yourself, a sort of self judgment. There is also a more complicated way to stay away of nightmares but it will be hard to explain in here, if you want to know how you can try to contact me :)

One way to stop having nightmares or have a deeper sleep is to invest in melatonin. With your doctor's permission, you can get melatonin at a local shop. Another way to have a deeper sleep and or calm your thoughts to decrease nightmares is to meditate. Just a quick 5-minute meditation before bed will do wonders.

Try removing clutter from your room. Organized room, organized mind. Try winding down activities such as reading a book, colouring, or listening to some relaxing music. Avoid foods high in sugar before bed. Use your bed only for sleeping. Do homework and other activities at a desk, table, or the couch (unless of course that's where you sleep). Keep your phone out of reach. Use background noise if it is too quiet. Get a nightlight if you're afraid of the dark. Make your space comfortable. Meditation.

Stopping nightmares are quite hard as I used to have some of them to, but it stopped when I used to lessen my worries and just be happy before going to sleep- reading also helps :)

Deeper sleep occurs as a result of the body and mind needing to recover - and thus (in moderation), I'd recommend maybe doing physical and mental exercises to exhaust yourself as this will help you attain a deeper sleep - whilst also improving your physical fitness and subsequently your mental health, and engaging your brain which is good for your executive functions e.g. memory, attention etc - its a win-win! If your nightmares are persisting and concerning you then I would recommend altering things in your life that could be perpetuating/ triggering the negative thoughts/ imagery that may be causing those to be salient themes in your dreams. Unfortunately, there is no solid theory and thus method of controlling yours dreams, thus all I can encourage is developing methods to help you address them positively/ adaptively when you have awoken.

Switch off! Quite literally - phones & technology are not only a distraction to falling asleep but unfiltered blue light can keep the brain active. If you put your phone in a different room to prevent the temptation of checking it, even better, but at least turn it to silent or do not distract :D Building up a regular sleeping routine can also help massively - humans are built to sleep from sunset to sunrise and while its been proven that this cycle maybe delayed (start and end later) in adolescents, aiming to sleep and wake at a regular time can make a big difference. (Given these times are 8 hours apart minimum!)