Sleep: it’s free. And we all want more of it, so why is it so hard to get? Specifically – that consistent, restorative, uninterrupted, eight-hours-a-night kinda sleep. Which is why we’ve enlisted Sydney-based sleep expert Olivia Arezzolo to solve our myriad of sleep concerns with our new editorial series Sleep Well Wednesdays. Check back each week and you’ll be off to the land of nod before you know it.

Depression is one of the most commonplace mental illnesses. In fact, research data shows it’s encountered by 300 million people worldwide, or 4.4% of the entire global population.

And as someone who’s gone through it myself, I can’t emphasise enough how debilitating the condition is…let alone the impact on your sleep. Specifically, 97% of those with depression report sleep disturbances.

97%.

If that’s resonating, read on. Today I’m sharing the how and why between this bidirectional link. You need to know that if this is happening for you, you’re completely normal.

Factor 1: how lack of sleep contributes to depression

For those lacking sleep, evidence suggests that mood suffers as a result. The degree of mood impairment reflects how much sleep you’ve missed. Specifically, the researchers tested the effects of 5 hours of sleep, per night, over the course of a week.

They found as the week progressed, with growing sleep debt, the worse mood became. Along similar lines, those with insomnia – aka chronically sleep deprived – are 10 times more likely to develop depression – as noted in academic research.

Factor two: how depression contributes to subpar sleep

For those with depression, clinical papers note the following:

• 97% report sleep disturbances
• 58% can’t fall asleep
• 59% wake up frequently through the night
• 61% wake too early (e.g. 3-4am) and can’t return to sleep

In terms of sleep architecture, clinical studies have found those with depression spend more time in REM sleep, less time in SWS and typically have a circadian misalignment – they sleep and wake later than normal.

Factor 3: how does your chronotype influence this?

Wolves in particular are at risk here: they are 4 times more likely to be depressed than lions, and twice as likely to be depressed compared to bears. However, as you can see, bear are twice as likely to encounter depression, compared to lions.

Along similar lines, evening-ness correlates with Seasonal Affective Disorder too, a subset of depression. 

Factor 4: what underlies it?

Essentially, they interact on several levels.

First, happiness hormones serotonin and dopamine are partially regulated by the circadian rhythm: so disrupting this delicate internal clock by lack of sleep or social jet lag impacts their biochemical pathways, and as a result, your mood.

Second, lack of sleep spikes cortisol, our stress hormone – initially, after a day or two of inadequate sleep, you’ll feel wired. However, with ongoing sleep loss, you’ll feel exhausted – directly due to cortisol.

Third, the reasons for impaired mood are sleep overlap. For example, 80% of those who are depressed also suffer generalised anxiety, which then has carry over effects into sleep. Similar findings have been found with stress, alcohol use, diet and use of pharmaceutical drugs – to name a few.

So – if this is you, I want you to take a deep breath. Let the above soak in, and know you’re completely normal.

A good bedtime routine can really help, so maybe consider trying my 7 step sleep-well wind-down to help you drift off.