Insomnia

Unable to fall sleep – its called Insomnia
Some of the key reasons that could cause insomnia include:

1) Stress and anxiety: Worring about Work, school, health, money or family can keep your mind overthinking and active at night

2) Environment: if your bed is unconfortable, too much light, noise, too hot or too cold temperature.

3) Lifestyle: shift work, alcohol or caffeine consumption before bed etc

4) Mental Health: Conditions like Depression and Schizophrenia

5) Indisciple in sleeping schedule

6) Physical Illness including pain

7) Fatigue for example due to too much physical activity

8) Lack of any physical exercises

This are just a few. What you need to understand is the relationship between Insomnia and other health conditions like Blood Pressure / Hyper Tension, Diabetes etc
The disease can cause Insomnia and lack of sleep can aggrevate the disease – visious cycle

Please do not ignore or take unprescripted sleeping pills. Consult a Doctor and get the root cause fixed.