I look outside. It is a grey Wednesday morning once again, and, wait … is it the Black Dog over there? Sightings of devilish black dogs were well documented and representative of the folklore in Britain and Europe in the 16th century. Ever since the expression ‘Black Dog’ has been coined as a metaphor of major depressive disorder. Only by association with Winston Churchill 400 years later the illness became known as something one can struggle with and have a success story to tell.

My point of view comes far outside of the land that is demarcated by the acknowledgements and citations in this book. It comes from a remote northern location where (a) there is either dark or grey, definitely not white or light, from November to January, (b) daylight saving (summer) time gives no benefit but disrupts sleep for days twice a year, and (c) 40% of the population have a problem with seasonal variation in sleeping, eating and mood. Such misalignments are indicated to predispose to mood disorders.

Depressive illness and suicide are pressing challenges for public health in the EU. Major depressive disorder affects about 13% of the population at some point in life. Depression can end in death from suicide. Of 1000 persons living in the EU, 11 complete suicide each year. It means one individual every 9 minutes on average. However, depression is a treatable disorder and suicide is a preventable act. With trials we have learned major depressive disorder can indeed remit quickly and remain in remission.

Treatment with light exposure and sleep deprivation has a good efficacy in the depressed. This book is a manual that concentrates on these two methods and encourages their exploration on in-patient units in the treatment of mood disorders. The focus is on hospitalized patients. It would not need to be, I think, as light therapy is easy to give to outpatients as well and wake therapy even three times a week can be ambulatory with cooperation. Sunny rooms or renovations with intelligent use of light control for exposure dynamics during the day open options for every house whether public or private.

This manual starts by giving basic information about the rhythms of life. Here, the reader notes that normal night sleep lowers mood in depressed patients. One is left with the ‘why’ question that is always so hard to address. The latter part of the night is the key that something specific and different from normal is triggered when the depressed stay awake during this sleep-sensitive circadian phase. The manual then continues by giving a rationale and practical details for each treatment. Clinicians could easily probe for chronotype whenever they meet a new patient. There is on the one hand, e.g. a table that gives a useful algorithm to schedule light exposures in the morning, whereas on the other there is a table about promising indications for light therapy, with which I disagree in part. Furthermore, why is it advised that sleep onset can be assisted with 0.25 mg triazolam for the phase advance of sleep following wake therapy? I would not advise so, bearing in mind the risk with this and its kind of medication.

The book has 116 pages in 15 chapters and 160 references to the literature. In addition to 33 figures, 10 tables and 7 appendices, 7 case studies, 7 research precedents and 3 flowcharts provide an oasis along the way. It is a big piece of information. Fortunately, the three authors are distinguished scientists and professionals who have the knowledge and ability to guide the reader through and make him feel refreshed at the end. It is well known that there is teen-peer pressure to stay up late in the evening, but did you know that there is a two-hour delay on average in sleep timing due to puberty and that this delay is greater for boys and girls. There is a serious argument for delaying the start of the school day, with which I disagree, but there might be a serious argument for shortening the duration of the working day in the winter as well. All this is fascinating. Reading this book offers good value for money, and hopefully the book will become well worn in the hands of clinicians and thereby help their patients.