Polar night

Dr. Nadja Albertsen is the ESA-sponsored medical doctor spending 12 months at Concordia research station in Antarctica. She facilitates a number of experiments on the effects of isolation, light deprivation, and extreme temperatures on the human body and mind. 

Sunday morning, 10:00. The base is quiet, like all Sundays. It’s the only day off, unless a holiday lands during the workweek.

People sleep in or relax. Someone, possibly Danish and wearing ski underwear, sunflower-print pajamas, and a down vest, reads scientific articles and enjoys an almost undisturbed internet connection.

Darkness engulfs the base. A look out the window reveals absolutely nothing, neither snow nor sky. The only visible light is a red lamp from one of the shelters close to the base; otherwise, blackness.

It’s been a month since the sun last went done, or last got up, if you prefer. The days following were marked by the spectacular night sky and a rather persistent hunt for Southern Lights, which we just managed to see. Concordia is not the best place for that kind of thing (but of course, we do not give up!).

Then the night sky was spoiled by a spectacular full Moon that transformed the landscape around the base into a white marsh. It was amazing.

But the darkness is also notoriously hard. In the first weeks after the last sunset, there was a bit of unrest and small conflicts among the group, which were not only quickly resolved but interestingly, brought the group closer together.

Perhaps the unrest was triggered by the uncertainty about what will happen in the coming months and how we, both individually and as a group, will react. We also have the long-lasting and absolute isolation and the thin air that we continue to feel. Imagine if we also run out of coffee…

Scientists are particularly interested in the psychological and physiological reactions to Antarctic winter from a biomedical perspective. Central to the studies is how people react to isolation and changed day-night cycle. Is there a particular personality type, for example, that handles these conditions psychologically and physiologically better than others and is there is a connection between the two? Spoiler: research so far suggests that there is, but more about this later.

I want to address more the tangible part of the problem: the darkness.

Most Scandinavians know the long summer days and corresponding short and dark winter days. We are aware of winter depression, light therapy, increased need for sleep and vitamin D supplements.

Many of us at the base already suffered from sleep deprivation even before the darkness settled like a quilt over Concordia. While some now feel an increased need for sleep, many are still plagued with problems of falling asleep or frequent or early waking.

Sleep problems can be part of the so-called winter-over syndrome, a kind of light polar depression, but it can also be due to lack of daylight. Whereas in the summer you can pull the blinds down to get a good night’s sleep, in the winter it is harder to turn on the Sun in the morning.

Studies have been conducted on the effect of artificial daylight on the circadian rhythm and sleep both here in Concordia and on other bases in Antarctica, and in the following I’ll discuss some of the results.

But first, let’s understand normal sleep. Sleep is characterised by reduced movement and activity, in which you are in a relaxed position and do not respond so quickly or strongly to external stimuli. Most importantly, you can wake up again.

Normally, we sleep between seven to nine hours a day, preferably at night. But the need for sleep varies individually and also by age and gender.

When you sleep, you go through several stages of sleep – light sleep, a little deeper sleep, deep sleep and REM sleep (or dream sleep) and you usually switch back and forth between the different types in cycles, each lasting around 90 minutes. The first part of the night is typically characterised by deep sleep and the last part of the night by REM sleep – and as written in a previous post, studies have found that, among other things, the order of sleep phases changes for people in Antarctica and that may affect sleep quality.

Sleep rhythm is subject the circadian process, or circadian rhythm – a kind of inner clock. This inner clock times the release of certain hormones, such as cortisol (the stress hormone) and melatonin, which is a hormone that causes sleepiness. This inner clock is very sensitive to light. In the retina, ganglion cells contain a pigment that is particularly stimulated by blue light and can signal to the brain that melatonin production must be suppressed. This is appropriate in the morning.

You can easily imagine that this hormone system and inner clock are confused in the winter, as the eye does not receive the same amount of light as in the summer and the production of melatonin is therefore not told to stop either.

Blue light is light that has a low wavelength, while white light, like the Sun’s light, is a mixture of all the colours in the scale. White light also contains blue light. Lux is an expression of brightness: in an apartment the brightness is often around 400 lux, while a sunny day is around 50 000 lux. In the winter, when we do not have Sun and primarily stay indoors, we don’t get nearly enough.

In a 2009 study at Concordia, the lights in the base were switched, first to white light for a week and then alternately blue-enriched white light, and finally ordinary white light for nine weeks. Participants filled in questionnaires during this time that asked about sleep quality, as well as sleep length and responsiveness measurements (in waking state). The study found that the ten participants became tired earlier in the day, slept longer, felt better at daytime and had better measured responsiveness when the light was enriched with blue light.

Similar results were obtained at Halley research station, where staff were exposed to bright white light for one hour each morning over 14 days. Since then, follow-up investigations have had similar findings. The researchers are no longer in doubt that light treatment has a positive effect on sleep disorders. Studies now also track how little light the body needs, since the energy required for the lamps is so expensive.

At Concordia we have three light therapy lamps, all shining at 10 000 lux, which means that you can handle a treatment of 30-120 minutes, depending on how close to the lamp you are. The lamps are quite large and clumsy and as there is not enough for everyone, they must be placed in strategic places where people can easily get to them and easily return them.

My biggest problem with regard to sleep has been frequent waking and poor quality of sleep – the two usually go hand in hand. As a doctor and researcher, I of course approach the problem scientifically. I use the lamp and make sure to exercise (not having coffee before bedtime also helps, among other things). Mounting the lamp in front of the treadmill lets me kill two birds with one stone.

And it actually works – my night’s sleep has improved and I have become a person again, with an internal alarm waking me at 05:00, just as it did in Denmark. Now I need to learn to go to bed when I’m tired.

Sleep well out there during the short summer nights!

To read Nadja’s adventures at Concordia in Danish, see her personal blog.

Sources:
Videnskab.dk: What is light?
Palinkas et al: Psychological effects of polar expeditions.
Jennum, P. et al: Knowledge Council for Prevention: Sleep and Health.
Curtain MVM et al: The effects of blue-enriched light treatment compared to standard light treatment in seasonal affective disorder.
Najjar, R.P. et al: Chronic Artificial Blue Enriched White Light is in Effective Countermeasure to Delayed Circadian Phase and Neurobehavioral Decrements.
Corbett, R.W. et al: An hour of bright white light in the early morning improves performance and advances sleep and circadian phase during the Antarctic winter.
Arendt, J.: Biological Rhythms During Residence in Polar Regions?