Bipolar disorder (previously referred to as manic depression) is a mental illness in which patients suffer from episodes of depression as well as spells of elevated mood, referred to as ‘mania’ or ‘hypomania’ when less severe. Sleep problems are common symptoms of both depression and elevated mood. When depressed, patients often describe insomnia – problems getting off to sleep, waking frequently during the night, or waking early before the alarm clock goes off. Some patients though describe over sleeping, finding it hard to get up in the morning and having naps during the day. During spells of elevated mood, a common symptom that patients have is a reduced need for sleep. This can sometimes lead to people not going to bed at all during the night.
Despite patients and doctors being aware of these types of sleep problems in bipolar disorder, surprisingly there has been very little research that has carefully studied sleep in patients. However, an important study has just been completed at the Northern Centre for Mood Disorders (NCMD). This was run by a PhD student, Andy Bradley, supervised by Dr Kirstie Anderson who is a sleep expert in the Newcastle upon Tyne Hospitals NHS Trust and Dr Peter Gallagher and Dr Hamish McAllister-Williams from NCMD.
Over the course of the last 3-4 years, around 50 patients with bipolar disorder and 50 people of the same gender and similar age but without a mental illness have been carefully studied. This included completing various questionnaires, using devices similar to a ‘FitBit’ for a couple of weeks to assess activity levels and amount of time asleep, wearing a device to assess blood oxygen levels during the night, and collecting urine to measure the hormone melatonin which is involved in regulating sleep.
As expected, the patients were found to have a high rate of sleep problems. While many patients said they suffered from insomnia, in fact over-sleeping was more common. However, in addition, a number of other sleep problems were seen. These included having disrupted sleep rhythms with an inconsistent pattern of the time of going to sleep and waking up, and ‘obstructive sleep apnoea’ (OSA). OSA describes a problem were people briefly stop breathing when they are asleep. It is most commonly seen in people who are overweight. It may be common in bipolar disorder because of the unfortunate side effect of several of the medications used which can cause weight gain. Overall, the various sleep problems overlapped a lot, with many patients having more than one.
The patients with abnormal sleep of any type were compared with the patients with normal sleep. Those with abnormal sleep had abnormal melatonin levels, lower mood and worse quality of life. This suggest that trying to help such patients with their sleep may be very important to help them have better lives.
In the study, patients also did tests of cognition (attention, concentration, learning, memory and so on). The relationship between sleep and cognition is the subject of a paper that is currently being written up.