Making Bipolar Disorder More Manageable: Using sleep patterns to predict mood swings

Sleep is incredibly important – for everyone. We all know the impact of a good night’s sleep: it can set us up for a great day or make everything feel more difficult. But, most of us recover quickly from a bad night; we go to bed earlier, learn from last night's late-night scrolling, or we (wishfully) ask our partner to learn the art of not snoring. We make minor adjustments, and our sleep usually recovers, as does our mood. We all go through periods of our lives with good and less-than-good sleep, but the ramifications of these patterns don’t go far beyond the next day. However, this is not the case for people with bipolar disorder. Or at least – it doesn’t appear so.

What is Bipolar Disorder?

Bipolar disorder affects 1-5% of the population and often debuts in young adulthood. People experience short and longer periods of extremely low or high mood, termed depression and mania, with varying degrees of impairment and impact on their lives, with periods of relatively stable mood in between. Symptoms vary between people, but depression is generally characterised by low mood, low energy, tiredness, slow thinking, and feelings of hopelessness and despair, guilt and shame. Mania, on the other hand, is characterised by very high energy, fast-paced thinking and movement, increased mood or happiness, euphoria, and anger, as well as increased confidence and, at times, delusional thinking about oneself or the world.

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Just as the symptoms can vary, so do the implications. In the more severe cases, people become suicidal and can take their own lives, or need hospital admissions to help with their symptoms. Very often, people suffer with mental pain for years, affecting their education, work, family, and quality of life. One thing most people will have in common is that the episodes of either mania or depression are unpredictable, painful, and require help to survive, figuratively, and in some cases, literally.

I have dedicated most of my career as a researcher and PhD student to finding ways of making the pain associated with bipolar disorder less severe, and one such area is predicting oncoming mood swings. Knowing when an episode is coming will ideally aid in preparing patients for the wave heading their way, encouraging them to activate any helpful behaviours or seek the medical help needed before it washes over them, thus softening the impact. At the core of it lies the hope that understanding the patterns of mood swings will give some power and agency back to people with bipolar disorder, make their illness feel more predictable and manageable, and less hopeless.

Sleep patterns

One thing that changes in bipolar disorder almost as much as mood is sleep – or rather, the need for sleep. Usually, people will have a lower need for sleep when they are manic, and a greater need when they are depressed. These changes in sleep needs and duration spent asleep had me wonder if the alterations occur before any other symptoms take hold. A bad night’s sleep is, after all, notorious for putting us in a bad mood.

I wanted to know if this perhaps could play a role in setting off the cascade of mood symptoms in bipolar disorder. If specific sleep patterns could be the canary in the coal mine, warning people that danger is heading their way, helping them raise the alarm when needed, and receive assistance before other symptoms take hold.

I approached this question from two angles: ‘what research has already been done on this topic and what were the findings?’ and ‘what can a year-long study examining mood states and daily sleep in people with bipolar disorder tell me?’.

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Looking at previous research, it was clear that other studies had found a pattern between sleep duration and mood in bipolar disorder; sleeping longer was often followed by a dip in mood and increased depressive symptoms, and sleeping less was frequently followed by an elevation of mood and increased manic symptoms. These patterns did not indicate that a depressive or manic episode was approaching, only that patients experienced an increase in those particular symptoms. It did show, however, that people with bipolar disorder are sensitive to their sleep changes and their mood is often linked to their sleep the night before.

For my second question, I was fortunate enough to gain access to a study that had already been conducted, and I examined its data for my PhD. In this study, participants with bipolar disorder were assessed every two weeks for new mood episodes, and they reported every day which hours they had been asleep the previous day. I looked at the weeks before any depressive or manic episode and investigated if any particular sleep patterns were present here, that perhaps might have predicted the episode. What I found was that participants would sleep more unstable hours in the weeks before a depressive episode. That is, there were more variations in the duration of sleep than in periods when they were not in any mood episodes (or about to enter one).

Now what?

What does this mean for people with bipolar disorder who wish to be able to anticipate their mood instability or episodes? My findings suggest that mood symptoms are linked to sleep duration, and it is reasonable to expect symptoms of either depression or mania on days after nights of much less or much more sleep than usual. Furthermore, if sleep duration appears to be very changeable, with alternating nights of lots or little sleep, the risk of developing a depressive episode is increased.

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In collaboration with their mental healthcare team, people with bipolar disorder may want to discuss what mood management strategies could be helpful when their sleep duration feels changed or variable, or what they may be able to do to help their sleep stay stable. Using tracking tools, such as apps or diaries, may help detect patterns that apply to them or identify other warning signs they may encounter before entering severe mood episodes.

Bipolar disorder is a complex and, in many cases, a chronic condition. It may never be entirely predictable, as there will always be other factors which could interfere with the onset of severe mood symptoms and episodes. However, understanding sleep patterns could offer clearer insight into the individual moods of each person, and make a significant difference in their quality of life and outcome of their illness. I hope that my research will provide a valuable tool in helping patients regain control over their symptoms, enabling them to implement strategies at the appropriate times and reduce the impact of this disorder.