Bipolar disorder represents a broad collection of mood disorders that share two fundamental characteristics: manic features that alternate with depression, and a recurrent course of illness. Over the years many clinicians and researchers have tried (some with more success than others) to carve bipolar disorders up into separate diagnostic groups, the two most important of which are bipolar disorder type I (mania and depression; affecting about 1% of the population) and bipolar disorder type II (hypomania and depression; affecting a further 1–2%).

In terms of clinical research, bipolar II disorder has always been the neglected sibling of bipolar I (classic ‘manic depression’), even though bipolar II is more common and, in many respects, just as morbid. The diagnosis and management of bipolar II is one of the most contentious areas of modern psychiatry: some clinicians struggle to take bipolar II seriously and are reluctant to diagnose it. The third edition of this brief text seeks to raise the profile of bipolar II and tries to clarify important areas of debate for busy clinicians. It will also be essential reading for patients and their families.

There are two sections: section 1 has 17 chapters covering some well-trodden ground plus several new areas; section 2 has no fewer than 18 ‘Management commentaries’, in which experts in the field of bipolar disorder provide answers to a series of clinical questions, such as ‘What is your preferred mood stabiliser for bipolar II disorder?’ and ‘Do you use antidepressants in managing bipolar II disorder?’. As someone who has spent a fair proportion of his clinical and research career working in the field of bipolar disorder, I thoroughly enjoyed these commentaries, not least because they highlight the inability of experts to agree on anything. A good example is the lack of consensus regarding antidepressants. I have always been very cautious about antidepressants in bipolar II, but the data and arguments put forward by Amsterdam & Lorenzo-Luaces (alongside the brilliantly nuanced discussion by Goldberg in section 1) have made me reconsider my position. This highlights an important point about heterogeneity within psychiatric diagnoses: bipolar II is not a single condition – some people with the diagnosis will do very badly on antidepressants, others will be able to take them with benefit and no ill effects. The problem is that clinicians have no reliable and objective ways in which to decide whether the individual patient in their clinic will benefit (or not) from antidepressant therapy. This kind of uncertainty highlights that bipolar II needs new large-scale collaborative clinical research – we can't go on trying to extrapolate treatment decisions from work on bipolar I disorder because the conditions, although similar, are clearly not the same.

There isn't room here to highlight all the topics covered but for me two chapters stand out: ‘Differentiating bipolar II disorder from personality-based dysregulation disorders’ by Paris & Bayes and ‘The role of well-being plans in managing bipolar II disorder’ by Orum. The bipolar/borderline debate takes up a disproportionate amount of time and energy within psychiatric practice – Paris & Bayes bring data, experience and common sense to this in a way that busy clinicians will find accessible. Similarly, Orum's exposition of well-being plans is an excellent, clinically useful guide to long-term collaborative self-management strategies and relapse prevention. If community mental health nurses were able to spend more time developing Orum's well-being plans with their patients – rather than working only on crisis interventions, as is increasingly the case in the UK – I think there would be real long-term benefits for patients, families and clinicians themselves.

A minor negative aspect of the book is that some chapters, most notably ‘The neurobiology of bipolar II disorder’, are underdeveloped and not entirely up to date, plus the opening chapters sometimes cover the same overlapping material (such as the nosological debate around the ‘bipolar spectrum’). I had also hoped to see a discussion or chapter on the importance of sleep, circadian rhythms and chronotherapies in managing bipolar II disorder.

Overall, this small book packs an impressive punch. The chapters are brief, clear and readable and Gordon Parker's ‘Rounding up’ at the end is a great summary of a fascinating area. I read this book over a couple of weeks on the morning commute and learned a lot. I think this may have made me a better clinician, but of course only time will tell.