Restless nights and blurrier days are extremely common. Around one in 10 people suffer from chronic insomnia, but many more will experience it from time to time over the course of their life. It’s perhaps, therefore, not surprising to hear that insomnia can take on many forms.

A new piece of research from the Netherlands Institute for Neuroscience argues that insomnia can be broken up into as many as five different categories.

"While we have always considered insomnia to be one disorder, it actually represents five different disorders,” Dr Tessa Blanken, lead author of the study, said in a statement. To their surprise, the five insomnia types didn't differ in their sleep complaints, such as difficulty falling asleep versus waking up too early in the morning. However, they did differ in their electroencephalogram response to environmental stimuli.

As reported in The Lancet Psychiatry journal, researchers asked over 4,000 people to self-report their experience with insomnia, as well as their life history and personality type. From this data, they managed to find a few trends that allowed them to break insomnia down into numerous different categories.

Here’s how the categories broke down.

-Type 1: highly distressed, ie. people who score high on neuroticism and prone to feeling tense or anxious. 

-Type 2: moderately distressed and reward-sensitive, ie. less distressed and respond strongly to rewards and positive events.

-Type 3: moderately distressed but reward-insensitive, ie. less distressed but also doesn't respond strongly to rewards and positive events.

-Type 4: slightly distressed with high reactivity, ie. low levels of constant distress, but very sensitive to stressful life events.

-Type 5: slightly distressed with low reactivity, ie. low levels of constant distress and low sensitivity to stressful life events.  

When the volunteers were measured again after five years, most kept to their same type. Whether sleeping pills or cognitive behavioral therapy worked better also differed between groups.

The team hope their study provides medical professionals and researchers with more scope when attempting to diagnose and treat people with insomnia. The research team also hope their categories aid scientists in locating the underlying mechanisms behind sleep disorders and other mental health concerns.

“Underlying brain mechanisms [between insomnia types] may be very different,” added Dr Blanken. “For comparison: progress in our understanding of dementia was propelled once we realized that there are different kinds, such as Alzheimer-, vascular-, and frontal-temporal dementia.”

However, it’s important to avoid self-diagnosing yourself. If you’ve been having trouble sleeping for a prolonged amount of time and it's starting to affect your life, then arrange an appointment with a doctor (and, whatever you do, don't just Google your symptoms).