Staying up late at night intentionally is not insomnia. If you find it difficult to fall asleep, or cannot sleep soundly for long, then it is indeed a case of insomnia. The inability to sleep can have terrible repercussions on your physical and psychological health.
A number of reasons could cause insomnia. Understanding the causes could help you identify your sleeplessness as insomnia and seek treatment right away.

What Health Issues cause Insomnia?
Here are some health problems of both the mind and body that can keep you awake 

1. Stress Chronic stress and worry born out of our tense lives is a direct cause of insomnia. Long-term anxiety, panic disorders, as well as PTSD can induce sleeplessness.
2. Irregular Sleep Patterns Your body would hate it if you deviate from the Circadian Rhythm – the body clock. It regulates the functions of your body, including your sleep patterns. But if you defy your body clock by sleeping at irregular hours – suppose you are staying up late to get some extra work done, or you may have opted for a night shift, or if you are experiencing a jet lag – then you will notice that when it is finally time for you to hit the bed, sleep will be elusive.
3. Depression Depression is a horrific psychological disorder that makes a person lose interest in life itself. And one of the indicators of depression is loss of sleep. It is not just depression, but also other illnesses that cause psychological turbulence such as bipolar disorder and obsessive-compulsive disorders, triggering insomnia.
4. Breathing Issues Sleep apnoea is a dangerous disorder that stops your breathing multiple times every night and will wake you up every time. Yet you will possibly not even remember waking up. However, this does disturb the quality of your sleep and affects your health adversely.
5. Dementia Dementia is accompanied by a gradual loss of memory. But sometimes people who are suffering from dementia display anxiety, restlessness or even aggressive behaviour when it is time for them to go to bed. This is called the sundown syndrome and it might even keep them up all night.
6. Pain Pain is one of the commonest reasons for losing sleep. Pain can originate due to any number of reasons – arthritis, a sprained joint, an injury, or if you are undergoing chemotherapy or radiotherapy, then it may keep you awake at night. This is actually a vicious circle because the inability to sleep will aggravate your pain. Talk to your doctor who will prescribe the appropriate pain medication.
7. Parkinson’s disease This disease is another reason behind insomnia. Parkinson’s disease interferes with your nerve signals and this might cause disruption in your sleep.
8. Menopause When a woman inches closer to her menopause, her body reduces the production of oestrogen and progesterone. This imbalance of hormones can trigger sleep loss.

How long can you go without sleep?

There is no data on how long a human can function without sleep. The longest someone stayed awake is 11 days. Usually, the body cannot last that long without some sound shut-eye. Your brain flushes out the waste matter its cells produce during sleep. That is why even 24 hours without sleep can make your brain sluggish and disoriented. If you stay awake for more than 48 hours at a stretch, your cognitive abilities will start failing you. Sleep is instrumental to a healthy mind and body. If you are experiencing insomnia, talk to a doctor immediately or look up some remedies.

In case you have a concern or query you can always consult an expert & get answers to your questions!