Since the early days when Emil Kraeplin defined the characteristic symptoms of bipolar disorder, a certain set of core features have been used to identify the disorder. Changes in mood, energy levels, and sleep all spring to mind. Then, there are other things… symptoms or signs that aren’t core to the identity of bipolar psychopathology, but might indicate a relatively higher or lower risk among individuals who are otherwise at a comparable level of risk for bipolar disorder. In other words, there are subtle signs that can help identify whether or not a diagnosis of bipolar disorder would be applicable to any given individual. Perhaps you’re looking out for these signs in your own behavior — or, perhaps you’re making observations about a friend or family member who you suspect may have the disorder. In any case, here are a few subtle signs.

You don’t have a consistent bedtime.

People with bipolar disorder are known for their changeable sleep schedules. Most people, when asked a question like, “When do you usually go to bed?” have a quick and easy answer. But if that question gives you pause and necessitates a complex timetable calculation in order to answer, it could be a sign that your circadian cycle is out of whack.

Bipolar disorder is one cause for circadian rhythm dysfunction. There are others — some, like non-24 hour sleep/wake disorder, cause a person’s bedtime to cycle predictably around the clock. But the changes in bipolar disorder are unpredictable. People may stay up late for weeks or even months, only to crash overnight into a routine of sleeping half the day or more. There is currently no way to know for sure when someone’s moods will change.

You have hyperfixations.

Have you ever become obsessed with a new hobby, concern, or passionate interest, only to grow bored of it and abandon ship before completing a grand project? Bipolar people are often known for their various pursuits (especially in the creative domain), as well as their mercurial sense of motivation to finish the tasks ahead of them. If you take on far too many tasks, or frequently change tasks without completing the initial task, you may be bipolar — or perhaps you just have what scholars call a “cyclothymic temperament”.

The term hyperfixation comes primarily from the ADHD world, but like many symptoms of ADHD, they’re a subtle sign of bipolar disorder too. Similarly, more generalized difficulties paying attention and staying focused are subtle signs.

You’re physically absent a lot.

As a rule, I don’t think people with bipolar disorder are emotionally absent from the lives of our loved ones — all too often, it’s actually the opposite, and our powerful emotions can impose themselves on people and situations. However, we are physically absent… quite a lot. Maybe you’re calling out sick from work again, or you’re about to drop a letter grade due to your absence from class; as a child, you may have been disciplined at school. This tendency to not show up to things can hinder achievement both personally and professionally.

You have neurological soft signs.

Neurological “soft signs” refers to certain problems with motor coordination and sensory integration that are observable on an exam from a neurologist. This includes difficulties with fine motor skills, errors in sequencing motor commands, and challenges with sensory perception. These problems are commonly talked about in reference to schizophrenia. However, it stands to reason that they also have at least a moderate association with bipolar disorder as well. Both bipolar disorder and schizophrenia are mental illnesses with a neurological or neurodevelopmental origin, and they have genetic overlap, as well as overlapping symptomatology (psychosis is the hallmark of schizophrenia and may be present in bipolar disorder as well).

Are there any other subtle signs you can think of?