The science of winter depression with Prof. Debra Skene – leading chronobiologist

**SPEAKER_1** (0:00)
Welcome to ZOE Science and Nutrition, where world leading scientists explain how their research can improve your health.
Winter is coming. Temperatures are dropping, clouds are descending, and the clocks are changing. Many of you might be worrying that the winter blues are on their way. But perhaps the icy grip of old man winter isn't inevitable. Perhaps we can work with our natural biological rhythms to fend off this blue phase. Well, today we're joined by Professor Debra Skene, section lead of chronobiology at the University of Surrey and a global authority on circadian rhythms. With over 190 research publications, she spent 25 years studying how light and timing affect our sleep, mood and metabolic health. After listening to this episode, we'll be armed with solid advice that will help you weather winter with a smile, maintaining good health and good mood until the warmth returns. Debra, thank you so much for joining me today.

**Debra Skene** (1:14)
Pleasure. Hello.

**SPEAKER_1** (1:15)
So we have a tradition here at ZOE where we always start with a quick fire round of questions from our listeners. And we have some very strict rules. We ask you to say yes or no, or if you have to, a one-sentence answer. You willing to give it a go?

**Debra Skene** (1:31)
Sure.

**SPEAKER_1** (1:32)
Can messing with your body clock lead to weight gain?

**SPEAKER_2** (1:36)
Yes.

**SPEAKER_1** (1:38)
Does when you eat influence your circadian rhythms?

**Debra Skene** (1:42)
Yes, we believe that as well, that I think timing of meals is very important.

**SPEAKER_1** (1:48)
Can the color of light influence our sleep-wake cycle?

**Debra Skene** (1:53)
Indeed, yes. Some colors are more effective than others.

**SPEAKER_1** (1:57)
Can light boxes help people keep their circadian rhythms on track?

**Debra Skene** (2:01)
I think so as well.

**SPEAKER_1** (2:04)
What's the most surprising thing that you've learned about circadian rhythms in your 25 years of research?

**Debra Skene** (2:10)
Probably the dim light has an effect. I always thought it was just bright light, daylight having an effect on your body clocks, but even dim light has an effect on the clock.

**SPEAKER_1** (2:22)
This is a big topic. To kick things off, let's go back right to basics. What are circadian rhythms and why do they matter for health?

**Debra Skene** (2:31)
It's more what are biological clocks, and we have them all over our body. It's critical that these clocks are synchronized with our life on Earth. For us, as people living on Earth, we've got this critical light-dark cycle that happens every 24 hours because of the Earth's rotation. What we need to do to stay in synchrony with this is that we have these biological clocks that are able to respond to the light-dark cycle, and in unison together would give you good health.

**SPEAKER_1** (3:13)
Can you help me to understand a bit more what a biological clock is that's in me?

**Debra Skene** (3:18)
Well, the first one that was discovered, the sort of master clock, so to speak, is in the hypothalamus, so within your brain. And it has a direct pathway from that clock in your brain to your eyes. So again, the light-dark cycle can enter your eyes and go down this nerve pathway to this master clock in your hypothalamus. And we know it's a clock because you can literally, not in people, but it can be taken out of animal bodies and put into a dish, and we can see the electrical activity of this clock oscillating. So it's a self-oscillating, independent clock that can literally tick in a dish.

**SPEAKER_1** (4:08)
It actually like literally is a clock going tick-tock, tick-tock in my brain right now.

**Debra Skene** (4:12)
Yeah. It has a 24-hour rhythm. So it will have a peak and a trough that takes about 24 hours to complete. So it is a self-sustaining oscillator.
And that's in the brain. And that's what we call our master clock or our conductor of all these clocks. Because more recently, we've discovered that they're clocks throughout the body, particularly in areas that are metabolized. So like we have a clock in the liver, clock in the pancreas, clock in muscles, in skin, and in adipose tissue. And it's all these clocks all around our body that need to all tick in time together. And this synchronized clockwork needs to be synchronized to our outside world.

**SPEAKER_1** (5:10)
Why do we need to have these body clocks inside us?

**Debra Skene** (5:13)
So the real reason we have clocks is to anticipate our next move. So they act as time keepers, because they're clocks, but they're telling us when to wake up, when it's appropriate to sleep, when we should eat, when we should not eat. They will anticipate spring and summer, daytime, nighttime. So with the clocks, our bodies can tell the rest of our body, you know, it's two hours before you should be going to sleep.