TEMPERATURE: This is a big problem, especially if you have a sleep partner. Everyone has different natural body temperatures, and usually men run hotter than women, but it can go either way. That can be a big issue if you have a different body temperature, because then no one’s happy. I wrote this article called “Split blankets, not beds,” where I said that you shouldn’t share the same comforter. Of course it’s nice to share, and I do that at some points, but it’s also important to have different bedding on your bed so you can have that lighter sheet or comforter to try to mitigate differences in body temperature. There’s also something called a chili pad. You put on half of your bed and it’ll dictate the temperature level on your half if you run at a different temperature than your sleep partner.

Melatonin supplements are widely recommended for various sleep conditions, but the best evidence is for help with sleep problems caused by shift work or jet lag. Melatonin is a naturally-occurring hormone that regulates the sleep-wake cycle in the brain. It is produced from serotonin when exposure to light decreases at night. It is used in conditions where sleep is disordered due to low levels of melatonin at night such as aging, affective disorders (e.g. depression), delayed sleep-phase disorder, or jet lag. 
A very common cause of difficulty sleeping relates to stress and the intrusion of stimulating substances and activities. You may have trouble falling asleep the night before a big test or presentation. In periods of emotional stress, such as after the death of a loved one, you may also have trouble sleeping. This is called acute insomnia. It usually passes when these stressors resolve. Similarly, stimulants such as caffeine and even nicotine can disrupt your sleep.

The other benefit of speaking with a healthcare professional is that you can discuss the use of sleeping pills. There are two major classes of prescription medications that can help you sleep: benzodiazepines and nonbenzodiazepines. The list of sleeping pills is long and includes drugs like Ambien, Lunesta, Sonata, Trazodone, Belsomra, and others. These should not be used longer than a few weeks and if insomnia persists, you may want to seek other treatment. In particular, you can ask for a referral to a psychologist who might be able to teach you cognitive behavioral therapy for insomnia (CBTI) techniques.

Use a blue light filter on your device. The blue light emitted by smartphones and tablets can be a powerful sleep disruptor. It suppresses your body’s production of melatonin and throws your circadian rhythm off, making it harder to fall and stay asleep. Luckily, many smartphones these days have a “night shift” feature that adjusts the screen from cool (blue) to warm (yellow) light, which is less likely to keep you up past your bedtime. Likewise, there are apps you can run on your laptop or tablet that reduce blue light. Some popular ones are f.lux and Twilight.