How Poor Sleep Can Turn Worry Into Depression

Disturbed sleep is an extremely common feature of generalised anxiety. This is distressing and debilitating enough in itself but it also plays a significant part in the feelings of depression that often accompany anxiety, as we shall explain.

Everybody appreciates a good night's sleep. But what constitutes a good night's sleep is much more complex than previously thought. Sleep is not just the brain turning off and resting. Every night, we need a quota of two kinds - slow-wave sleep and dream sleep (also called rapid eye movement or REM sleep because our eyes dart around behind our closed eyelids during this phase). During slow-wave sleep, the day-to-day wear and tear on our bodily tissues is repaired; brain cells are recharged with sugars and our immune system is refreshed. But, in dream sleep, our brain services our emotion-al intelligence system. In effect, dreaming is an inbuilt super stress-control mechanism, one of nature's most incredible developments, without which complex mammals like us could not have evolved. So, to use a computer analogy, slow-wave sleep repairs the hardware and dream sleep repairs the software - our thoughts and emotions.

After 12 years of research, trying to puzzle out why we evolved to dream, a social psychologist, showed that the role of dreaming is to deactivate the emotional expectations that we get worked up about during the day and which are still taking up space in our brains when we fall asleep. He discovered that what needs discharging are not the arousals that were expressed during the day, perhaps by having a heated argument with our partner, or taking evasive action, such as steering round and managing to avoid a dramatic motorway accident; it is the arousals that aren't expressed or acted out that produce dreams.

These arousals stew away all day below consciousness, waiting to be dealt with, and, if they are still there when we fall asleep, the arousal pattern is completed by being acted out metaphorically in our dreams. This frees up our brains to face the next day's emotional concerns. In other words, we dream out the emotionally arousing expectations, which, unconsciously, our emotional brain was still expecting to have happen.

This is one of those scientific discoveries that is easy to confirm from your own experience. Every day we generate countless expectations - emotional arousals, positive or negative - that don't work out. These can range from major ones, such as setting one's heart on a new house but not knowing if things are going to work out, to minor ones, like considering for a moment taking a proffered piece of cake and then thinking better of it.

Thoughts about the house would keep surfacing, even though we might instantly forget the cake, but both expectations would remain live in the brain at an instinctive, emotional level. This is because a primitive urge has been activated - to move towards something that is desired (the house) or to eat something (the cake) - and, just like other primitive survival urges (for sex, warmth or safety etc.), it has to be discharged in some way or another, once aroused.

This is as true for other mammals as it is for us. If the urges didn't get discharged, our survival instincts would weaken. For what would be the point of having the instincts that urge us to eat, drink, run away, have sex, etc., if we ignored them most of the time? Yet we do override them a great deal of the time because we don't eat every time we see something that whets our appetite or have sex every time we see a person that attracts us. Clearly, we still need those instincts available to us for the right times and places. So nature's clever way to keep instinctive programmes intact is to 'act out' or complete in our dreams the expectations that were not fulfilled while we were awake.

The brain can only do this when all the senses are shut down, as they are in REM sleep. And, because we can't fulfil the expectations in 'real' time, the brain uses metaphors, patterns drawn from memory, that correspond emotionally to the expectations not acted out.

The unfulfilled expectations that give rise to dreams can be surprisingly varied. For instance, even seeing something on television that makes us angry or alarmed can be sufficient to generate a dream. (As parents are well aware, children often wake up from nightmares generated by something scary seen on the telly.) More importantly, for our purposes here, an almost bottomless pit of unfulfilled expectations is produced by ... constant worrying. And that brings its own special problems.

Let us imagine that Elizabeth, instead of dropping off into a comfortable, soothing sleep when she goes to bed, lies there every night with different worries going round and round in her head:

"What if I don't get the car to the garage the minute it opens. I'll have to wait in the queue to book it in and then I'll be late for the train. Then I'll have no time to get the room prepared for the meeting. And what if I don't get a seat on the train? I can't stand with my bad back. But it would be so embarrassing to ask for a seat! Lucy's got her mock maths GCSE tomorrow. I wonder if she packed her calculator. I'm sure I saw it downstairs, when she was studying. Did she pick it up? I think she must have. Or did she? I must remember to check the table when I get up. Perhaps I should do it now? No, it's too cold. Oh, I'd better. No, it will disturb the cat, if I go down there. He'll think I'm going to feed him ... "

By thinking all this, Elizabeth is reliably building up more and more software maintenance for her poor dreaming brain to carry out. And that is added to all the worries that have been whirring around in her head all day that are already in the queue.

Dream overload

Dream (REM) sleep is a wonderful mechanism. But, just as two aspirins can be helpful in curing a headache, whereas taking the whole bottle would be harmful, so the right amount of REM sleep accomplishes the emotional repairs required but too much is counter-productive. In addition, if you give the dreaming brain too much work to do, it is forced to up the amount of REM sleep you have each night, which isn't healthy.

The normal sleep pattern is to start the night with slow-wave body-repair sleep, followed about 90 minutes later by our first period of REM sleep, which lasts about 10 minutes. As the night goes on, we gradually have less slow wave sleep and more REM sleep, culminating in about half an hour of REM sleep just before we wake up in the morning (which is why we sometimes remember the last dream we have had). As a rule, though, we usually forget our dreams, because they represent expectations that didn't get completed in real life and therefore we don't want them stored in memory, as if they had been.

However, research has shown that depressed people who worry a lot have their first REM sleep just 20 minutes (or at most 50) into the night, and it can last for almost an hour. They then continue to have more and longer periods of REM sleep (and more intense dreams) until the brain can take no more and they wake in the early hours, even more exhausted than when they went to sleep. Then, once awake, they start all the worrying all over again.

We have an electrical signalling system in our brains -sometimes called the orientation response - that alerts us to sudden changes in our environment. (It is this that would have drawn our attention to the sound of footsteps or the darting movement in the alley that we described earlier, when discussing the amygdala's alarm system role.) This same signal is also set off at the start of and during dreaming, alerting us to the fact that there are undischarged emotional arousals which need de-arousing through dream content. Unsurprisingly, this signal goes off at an amazing rate in people who worry almost continually. Each time we respond to this signal, however, it draws on our motivational energy, of which we only have a certain amount. And, as excessive REM sleep pretty well uses this up, it is no surprise, then, than incessant worriers all too often wake in the morning feeling not just exhausted but depressed and lacking in the motivation to get them going.

Quite naturally, this provides something new to worry about. "Why do I feel like this? I went to bed early. And I know I had quite a bit of sleep. Why don't I feel refreshed? Why is it such a huge effort just to get out of bed and go and put the kettle on? Perhaps there's something seriously physically wrong with me?"

If this is you ...

Well, yes, something is physically wrong - at the moment. Your sleep pattern is out of balance, leaving you short on slow-wave body-repair sleep while your dreaming brain is in overdrive, running itself ragged trying to discharge all the arousal caused by your worrying. No wonder you don't feel good. And the longer it goes on, the greater the wear and tear on your body, as it is also under siege from all those perpetually circulating stress hormones.

Quite a dramatic scenario, isn't it? And it stems entirely from all that fretting, worrying and dread. And although your energy stores gradually fill up somewhat during the day, they quickly become depleted again when the next bout of emotional arousals comes up for discharge in dream form that night. For dreaming doesn't solve problems. It isn't intended to. It merely completes our unresolved emotional expectations so that we can start the day with a fresh 'slate', in terms of emotional arousal. By starting the worry cycle all over again, we undo all that work.

But this needn't be a permanent state of affairs. Indeed, we have found that simply knowing all this is often the spur that people need to enable them successfully to take the steps which we describe in Part 2 to stop the worrying.

Continued in this article: Post traumatic stress reactions