If you want to prevent insomnia, you need to prevent the factors, that cause insomnia, first.
Physiologic factors that contribute to the development of insomnia are mostly difficult to be given a solution.
Some does not have a solution at all.
In this case, it's almost impossible to prevent insomnia.
Here are some of the physiologic causes of insomnia and the solutions, if applicable, that could help you prevent insomnia from developing.
1.
Food allergies According to an article at holisticonline.
com, allergies to certain foods can cause histamine to be released in the brain which can cause a disturbance in a person's biochemistry, and can, in some cases lead to sleep disturbance.
In the brain, histamine replaces neurotransmitters, but because it does not function like other neurotransmitters, it creates a dysfunction in the biochemical pathways of the brain (these are responsible for thinking, mood, and behavior).
When these pathways are disrupted, one of the symptoms is insomnia.
Solution: Obviously, the best way to deal with this is to avoid foods that trigger your allergy.
Treating your allergy with antihistamines may not be the best way because there are some antihistamines which cause insomnia as a side effect.
2.
Brain Lesions According to a study, here are some types of brain lesions that can cause insomnia.

• Mesodiencephalic bilateral infarcts - induce a variable degree of damage to both waking and non-REM sleep networks producing an abnormal waking and sometimes a stage 1 hypersomnia reduced by certain drugs.
  It can be considered as a syndrome of catecholaminergic deficiency.
  
• Central pontine lesions- induce REM and non-REM sleep insomnia with bilateral lateral gaze paralysis.
  
• Bulbar stroke- leads to frequent sleep breathing disorders.
  

Solution: None.
Brain lesions are among some things that one can't really prevent.
It could be because of an accident (blunt force to the head or surgery) or it may be induced (for medical purposes).
3.
Breathing difficulties such as asthma and sleep apnea Asthma causes airways to shrink while sleep apnea stops breathing for a while.
Both conditions decrease oxygen intake of an individual which can be remedied by conscious breathing and so will require a person to wake up from time to time in order for conscious breathing to happen.
Solution: Asthma can't be cured but it can be managed.
Proper management of asthma can prevent insomnia.
As for sleep apnea, there are a lot of ways to treat it.
Try surgery or alternative methods.
Continuous positive airway pressure (CPAC) is also highly recommended.
Properly managing these conditions can help you prevent insomnia.
4.
Chronic Obstructive Pulmonary Disease (COPD) Sleep disturbance in COPD is usually related to nocturnal cough, wheezing, and shortness of breath due to worsening of pulmonary mechanics and gas exchange during sleep.
This results to frequent arousals and awakening reducing total sleep time.
Solutions:

• Pursed lip breathing can minimize the symptoms of COPD
• Inhaled glutathione therapy is known to ease most of the symptoms of COPD
• Consider alternative medicine such as homeopathy, herbs, and massage
• Avoid eating dairy products during daytime to reduce mucus build-up at night.
  

5.
Decreased melatonin Melatonin is the hormone responsible in regulating our biological clock which regulates sleep-wake cycles.
As we age, our body starts to produce less melatonin thus, decreasing the ability of our biological clock to regulate our sleep-wake cycles.
Insomnia caused by a decrease in melatonin is common among the elderly.
Solutions: Prevent insomnia by increasing your melatonin production.

• You can buy melatonin in the form of drugs.
  In some countries, you need a prescription for these drugs.
  
• Exposure to natural light during the day increases melatonin output during the night.
  Studies show that physical exercise boost melatonin
• Eat foods rich in melatonin such as ginger, tomatoes, bananas, barley, oats, sweet corn, and rice.