It is a sleep disorder which can be present either because of some other health issue you have or can be the primary issue that you are having (nothing else is causing it). In the cases where you are suffering from lack of sleep or sleep deprivations which is brought forth by another medical condition then this type of is called a secondary insomnia.
It is the most widespread type out there.
Hormonal Changes Such As Changes During Pregnancy May Cause Secondary Insomnia
Health Problems Which Can Cause Secondary Insomnia:
Any condition which generates pain. Most often found among people with chronic pain.
Any condition which disturbs and prevents you from having regular sleep such as Restless Leg Syndrome or Headaches or Sleep Apnea or Asthma or Depression, etc.
Any condition which makes you itch yourself continuously. Again, worst in chronic itching.
Biological changes in your body such as hormonal changes such as during pregnancy or menstrual cycle.
Chemicals; either side effects from taking pills, drugs, or food and drink such as stimulants, junk food. Basically all chemicals which are harming your body’s regular functioning.
Treating Secondary Insomnia
As per definition, this condition is haunting you due to another issue that you have and therefore the smartest action to take is to treat the root problem and the insomnia will automatically go away as there would be no longer a need for it to exist.