Sleep apnoea and depression are both characterised by tiredness, daytime sleepiness, irritability and lack of motivation, among other things1. But is the similarity more than skin deep? And could treating one help to resolve the other2? Researchers are trying to answer these questions in a bid to improve the diagnosis and treatment of both conditions. We take a look at the story so far.
The link between sleep apnoea and depression
Untreated sleep apnoea disturbs your sleep and leaves you tired and moody during the day. It’s also responsible for less visible dangers. For example, it increases the risk of chronic health problems including heart disease, obesity, high blood pressure, Type 2 diabetes, stroke and depression3.
The relationship between obstructive sleep apnoea (OSA) and depression is complex and difficult to unravel4,5. But there does appear to be a causal relationship6. In 20037, a review of data from nearly 20,000 Europeans aged 15 to 100 showed that people with depression were five times more likely to have a breathing-related sleep disorder than people without depression. And in 20069 and 20128, researchers identified similar relationships in laboratory-based studies: depressed individuals were significantly more likely to have been diagnosed with OSA, and even relatively minor sleep-disordered breathing was contributing to or exacerbating depression.
CPAP vs depression
As a result, researchers started exploring whether treating sleep apnoea could help people suffering from depression9. A 2007 study4 showed that treating OSA with continuous positive airway pressure (CPAP) therapy could significantly reduce depressive symptoms. Since then, numerous studies8 have shown that treating SDB with CPAP has positive knock-on effects on depression. For example, in one study, only 4% of patients still had clinically-significant depressive symptoms after CPAP treatment and none of them reported consistent suicidal tendencies during the follow-up phase6. Even better, these are long-term improvements that persist when patients are followed up after six months or even a year.
Room for confusion, room for hope
Clearly, not everyone with SDB is affected by depression, and not all depression is caused by SDB. However, many symptoms do overlap5 and there’s a significant overlap between patient populations too1,2. Depression is difficult to treat. This is especially true for patients with OSA, as some anti-depressant medications can suppress breathing and worsen OSA4. Given that both disorders are very common, difficult to treat, and under-diagnosed5, a deeper understanding of the relationship between them could decrease rates of undiagnosed and untreated disease8,9 and improve the efficacy of treatment4. And that has the potential to improve the lives of millions of patients.
If you’re struggling with depression or negative mood or think you might be affected by sleep-disordered breathing, ask your doctor for help.