10 causes of poor sleep

1. Stress. Concerns about work, school, health, finances or family can keep your mind active at night, making it difficult to sleep. Stressful life events or trauma – such as the death or illness of a loved one, divorce, or a job loss –may also lead to insomnia.
2. Disruptive travel or work schedule. Your circadian rhythms act as an internal clock, guiding such things as your sleep-wake cycle, metabolism and body temperature. Disrupting your body's circadian rhythms can lead to insomnia. Causes include jet lag from traveling across multiple time zones, working a late or early shift, or frequently changing shifts.
3. Poor sleep habits. Poor sleep habits include an irregular bedtime schedule, naps, stimulating activities before bed, an uncomfortable sleep environment and using your bed for work, eating or watching TV. Computers, TVs, video games, smartphones or other screens just before bed can also interfere with your sleep cycle.
4. Eating too much late in the evening. Having a light snack before bedtime is ok, but eating too much may cause you to feel physically uncomfortable while lying down. Some people also experience heartburn, which is a backflow of acid and food from the stomach into the esophagus after eating, which may keep you awake.
5. Side effects of medications. Chronic insomnia may also be associated with medical conditions or the use of certain drugs. Treating the medical condition may help improve sleep, but the insomnia may persist after the medical condition improves.
6. Mental health disorders. Anxiety disorders, such as post-traumatic stress disorder, may disrupt your sleep. Awakening too early can be a sign of depression. Insomnia often occurs with other mental health disorders.
7. Medications. Prescription drugs can interfere with sleep, such as certain antidepressants and medications for asthma or blood pressure. Some over-the-counter medications – including some pain medications, allergy and cold medications, and weight-loss products – contain caffeine and other stimulants that can disrupt sleep.
8. Medical conditions. Examples of conditions linked with insomnia include chronic pain, cancer, diabetes, heart disease, asthma, gastroesophageal reflux disease (GERD), overactive thyroid, Parkinson's disease and Alzheimer's disease.
9. Sleep-related disorders. Sleep apnoea can cause pauses in breathing periodically throughout the night, interrupting your sleep. Restless legs syndrome can cause unpleasant sensations in your legs and an almost irresistible desire to move them, which may prevent you from falling asleep.
10. Caffeine, nicotine and alcohol. Coffee, tea, cola and other caffeinated drinks are stimulants. Drinking them in the late afternoon or evening can keep you from falling asleep at night. Nicotine in tobacco products is another stimulant that can interfere with sleep. Alcohol may help you fall asleep, but it prevents deeper stages of sleep and often causes awakening in the middle of the night.

Read here about 9 ways to restore good sleep