As part of Depression Detectives, we’re holding weekly Q&As with scientists and experts who work on depression or related topics. Our Q&A last week was with Daniel Smith, a psychiatrist from the University of Edinburgh who is part of a sleep research project called SCRAMS (Sleep, circadian rhythms and mental health in schools). We were also joined by Heather Whalley, who works with Daniel on SCRAMS and led our Q&A on brain imaging.
Daniel: Evening everyone. I’m a psychiatrist and researcher with a special interest in bipolar disorder. My interest in the connection between disturbed sleep/circadian rhythms and mood disorders includes research on the genetic overlap, research on sleep and depression in young people and more recently an interest in ‘chronotherapies’ such as bright light therapy for bipolar depression
Depression Detectives member N (DD N): Could you tell us what the genetic overlap is?
Daniel: This is about common genetic variants that slightly increase our risk of sleep disruption also being associated with increased risk of mood disorders. It’s due to many of these variants combined, rather than single genes
DD E: So change in sleep pattern can trigger depression in bipolar?
Daniel: Yes – sleep deprivation is a common trigger for mania. I should add that this is also about disrupted rhythms of rest/activity, not just sleep per se
There is some evidence that genetic factors that predispose us to sleep problems are shared with genetic factors for depression and bipolar disorder, and traits such as mood instability
DD E: Oh interesting so it plays a role in the highs and lows of mood?
Daniel: I think anyone will have changes in their mood the day after a bad night’s sleep but people who are vulnerable to depression and bipolar disorder are probably more sensitive to this and less able to compensate. A classic example is that crossing time-zones in air travel can really disrupt our circadian rhythms (and gives most people jet lag) but people with bipolar disorder can become much more unwell
DD E: does melatonin treatment help with bipolar the same way some people use it for jet lag?
Daniel: The evidence for melatonin in bipolar disorder is pretty weak – it sees that people with bipolar disorder need a more robust way to regulate their sleep patterns
DD S: I’ve heard that sleep deprivation can help depression. For example see this article. My question is, does this apply to everyone, or to a subgroup of people with depression – notably, does it apply only to people who oversleep when depressed? And is there consensus on what ‘sleep deprivation for depression treatment’ should consist of e.g. one 24h without sleep? A longer period with an hour or two less each night? It seems like it would be worth trying…but are there risks? (if you’re undiagnosed bipolar I would think this could trigger mania, for instance)
Daniel: The idea of using sleep deprivation as a treatment for severe depression has been around a long time and it’s good to see some more recent studies. Overall, it can be effective for some people but I think it’s fair to say that the effects are often short-lived and this is not an easy treatment to deliver (it needs lots of staff time and resources, for example)
DD E: staff time to keep the patients awake? And can people do sleep therapy by themselves?
Daniel: So it need quite intensive nursing to ensure sleep deprivation
DD N: Sleep is often mentioned as a symptom/factor in depression, but it seems people go either towards sleeping way more than usual or struggling to sleep at all. Is there any indication as to why people experience different effects on their sleep?
Daniel: In general (but not always) depression is associated with worse sleep and bipolar depression with more sleep
Heather: That’s a really good point, and some of the difficulties in depression research (I work with Daniel) – people experience different and sometimes opposite symptoms, like increased or decreased sleep, and increased or decreased weight for example. We are only just starting to tease these things apart.
DD S: Do you think it’s because actually people are experiencing different types of depression? Or that different people respond differently to the same thing? Or that there’s almost a biological or behavioural coin toss somewhere, and the same person could go either way?
Daniel: Very good question – obviously it’s complicated, mostly because depression is not a single disorder – more likely a collection of slightly different disorders with some common symptoms
Heather: I’d like to say we know, but we don’t as far as I’m aware. There have been genetic studies trying to tease these things apart (to see if these might be different subtypes based on the type and direction of symptoms, and different underlying causes ), but we’ve only recently had sample sizes to do this kind of analysis, and I’m not aware of anything convincing as yet, tho Daniel might know more….
DD S: How would you even study that then? What kind of experiments would you do?
Heather: there are v big studies like one called UK Biobank which has genetic data and some information on depressive symptoms, but often because of the scale (0.5 million people) some of the nuanced symptom data is lost – but its a place to start…So essentially looking to see what large datasets there are with the right sort of information.
DD C: Could you tell us a bit more about how chronotherapy works? And is this suitable only for some people or for everyone who has depression and has sleep problems?
Daniel: Light boxes in the winter can help most people with mild seasonal depression or lack of energy in winter and bright light in the morning is now being seriously investigated for bipolar depression
DD A: Hi Daniel, is there much research about starting school at a later time for teenaged children because they are unable to sleep long enough when school starts at 9am?
Daniel: Our SCRAMS group are reviewing the literature on this but overall it looks likely that even a small delay in schools start times is beneficial for teenagers, who are not programmed to wake up properly until about 11am
DD S: Teenage me feels vindicated here!
DD C: Not just teenage me. All my life I’ve had this problem. I wonder if it’s related to poor quality sleep in adulthood, say because of sleep apnoea?
Daniel: yes – all sorts of causes
Heather: There is increasing research here I think, and discussions not just about later start times, but thinking about the content/subjects for the earliest lessons
Daniel: Also, we shouldn’t be expecting teenagers to go to sleep at 9 or 10pm when their body is telling them 11pm or midnight
DD N: This makes me wonder whether teenagers who are living in situations without artificial light have the same difference in sleep schedule as teenagers living in electric-lit houses!
Daniel: Too much light at night for teenagers is a very bad thing!
DD N: Is too much light at night worse for teenagers than adults?
Daniel: Yes – I think this is very likely true
Heather: interesting 🤔!
Heather: Someone posted during the week about if we know what comes first, the sleep problems, or the depression. Do we have any info here Daniel?
Daniel: Not sure – sleep problems are a trigger and a symptom, so hard to untangle this
DD N: Do you have any thoughts on what kind of research would be needed to figure it out?
Daniel: I think we need very carefully designed prospective follow up studies of large numbers of young people and collecting objective data on sleep and mood to see what comes first and then what happens after a depressive episode
DD S: From a discussion thread in this group, it seemed like a lot of us were natural ‘owls’. Is there any research on chronotypes and depression? Are naturally late-rising people more prone to depression? (Either because there is some connection between the causes, or because late-rising people are more likely to experience sleep deprivation, in ‘9-5’ jobs/schools?).
Daniel: Sorry to say that night owls are more likely to have a range of adverse health outcomes, including more depression. Evening chronotype makes it more likely to experience circadian disruption
DD S: Do we know why the worse health outcomes?
Daniel: Because the circadian system controls all of our biology – from eating to immune response to hormone release – it affects all sorts of functions
DD S: So you’re saying evening people have worse health outcomes because their circadian rhythms are more likely to be disrupted. But is that BECAUSE school and office hours, etc, are set to suit morning people? ie it’s the social setting that causes the health outcomes effects, rather than the chronotype per se?
Daniel: I think some people cope well with our (very unnatural) 24 hour modern living – these people are more often morning larks, so yes modern society suits larks.
DD S: I’m now wondering if there’s any research looking at this during the pandemic? I mean, a lot of people have been working from home, and more easily able to have a sleep schedule that suits them. Have owls found this has improved some aspects of their health?
(I realise it’s probably difficult to separate the sleep schedule from everything else that’s been going on….)
Daniel: I’ve seen a fair bit on sleep during the pandemic, eg, everyone is having more vivid dreams (because they are sleeping more naturally without alarm clocks and are more likely to wake up during a dream)
DD S: We’ll that is fascinating! I’d always assumed we naturally wake up at the end of a dream. Is that not the case?
Daniel: we dream about 5-6 times per night, during REM sleep which cycles veery 90 minutes but we dream more at the end of the night
DD S: And our brain doesn’t ‘wait’ to wake us up after the dream has finished? But just kind of wakes us up as it’s still going on? (Now I’ve typed that, I’m wondering what it would mean to finish a dream. It’s not like it’s a film, with a narrative arc…)
Daniel: it’s just that sleep becomes lighter as the night progresses and we are more likely to wake towards the morning
DD S: What wakes us then? If it’s not the dreaming brain? Who/what decides it’s time to wake?
Daniel: It’s a natural biological cycle of deep and light sleep that recurs 6 times per night
DD S: hence waking between 3 and 4 am being quite common?
DD C: Is the chronotype completely fixed or could a night owl turn into a lark?
Daniel: young people are morning larks, then teenagers are evening owls, then older people are morning larks again, so it changes through life and can be modified by training
DD A: My children (8 and 4) are natural night owls, like me. They will sleep reliably around 10pm and struggle to wake up. Should/could I be actively training them to sleep and wake earlier?
Daniel: I don’t think so – probably best to respect their natural rhythms as far as possible – they will change as they get older
DD E: People who regularly change their sleep pattern, e.g. to do day and night shifts on rota, are they more likely to get mental health problems doing that?
Daniel: yes, I think it has been shown to be not good for health generally, fighting natural circadian rhythms. In general shift work is very bad for our long term mental health and people with mood disorders should probably avoid shift work if possible
DD L: Is the quality of sleep different in people with depression? E.g., less deep sleep.
Daniel: In general yes – less deep sleep, more waking etc
DD E: Reading your answer on bipolar sleeping later in the morning resonates with me and I find I can go to sleep fairly easily in quite a good settled mood, but wake in the morning feeling down and depressed. Is this typical for bipolar disorder?
DD M: I’m not bipolar but can also experience this
Daniel: Yes – in bipolar depression (and more severe unipolar depression) people have more diurnal variation in mood , usually feeling much worse in the mornign and better as the day goes on
DD M: how would one determine ‘more severe unipolar depression’ please?
Daniel: Just more severe symptoms, more debilitating fatigue, loss of appetite, weight loss, preoccupations with dying etc
DD E: During times of depression are dreams on more of a depressed theme?
Daniel: I’m not a Freudian (much) but I think that could be true for many people!
DD M: lots of mine are anxiety dreams. If I remember them
DD L: Does lack of sleep play a role in the development of post natal depression?
Daniel: Yes indeed – an important factor among many
DD E: One more question – does depression medication affect quality of sleep in a therapeutic way? Or does it interfere/block sleep quality
Daniel: It depends on the medication I think – some drugs, eg, benzodiazepines do provide good sleep and others, eg, SSRIs might help sleep but it can be a bit more superficial/less satisfying
DD C: I can certainly affirm that SSRIs gave me incredibly lucid dreams, especially ones where I was flying. I was also often aware in the dream that I was in fact dreaming and could to some extent take control eg I think I’ll fly over there now. Unfortunately it was shortly afterwards that I would wake up.
DD N: Do you think there are any major gaps in the research in this area?
Daniel: In general I think psychiatry has not paid enough attention to how manipulating sleep patterns can be therapeutic, eg, using light and other chronotherapies – part of the reason is that there is very little money in this for drug companies
DD S: Ooo, I had one more question. I find that if I walk outdoors each day (my usual form of exercise), then my sleep is much better. We know that exercise is good for depression. But do we know if the exercise directly helps the depression? Or is it because the exercise makes your sleep better, and that helps with the depression?
Daniel: My strong view (as yet unproven) is that outdoor exercise helps our mental health via an indirect effect on better sleep caused by morning light exposure
Heather: Just posting a link here as one output from Daniels group- a comic type explanation of sleep, biology and mood aimed at teens
DD N: That’s all we’ve got time for! Thanks so much for coming Daniel, this has been really great
Daniel: Thanks everyone – sleep well!