Let’s say you grow up in a family of champion sleepers, yourself included. At college, you sail through rowdy dormitory life sleeping like a log. Job interviews, stressful to some, don’t faze you. By 27, you’ve landed a good job and in a few years earned enough for a down payment on a house. Sleep is still dependable and stays that way for a decade.
Then, coinciding with a move and the birth of a second child, you find yourself wide awake at your normal bedtime, staring at walls. Soon this becomes the rule rather than the exception. Before you know it you’ve developed chronic insomnia. How can sleep go from good to bad so quickly?
How Insomnia Develops
For decades sleep scientists have been trying to work out how chronic insomnia develops. The main model they’ve proposed looks something like this:
- Predisposing factors are presumed to exist in everyone who develops chronic insomnia. They include such observable factors as (a) parental history of insomnia, (b) high sleep reactivity (a tendency to sleep poorly before and after stressful events such as giving a speech or having an argument; and to be highly reactive to caffeine, jet lag, and interpersonal stressors), and (c) poor health—all associated with biological challenges to sleep.
- Precipitating factors come next: major life stressors that often trigger an episode of insomnia such as a job loss, marriage, or relocation to a different town.
- Perpetuating factors are the habits some people then adopt for insomnia relief—taking naps, going to bed early, sleeping in on weekends—that actually make their sleep worse.
- Conditioned arousal of the cerebral cortex is the final step in in the process. Lying awake for long stretches of the night opens the door to worry and rumination. This brain activity can spill over into sleep and keep insomnia going indefinitely.
This may be how chronic insomnia develops in some people. There may also be alternative pathways to insomnia. A large community-based study (Evolution of Pathways to Insomnia Cohort) was recently conducted to figure out what those alternative pathways might be. Working with data from that study, Michigan researchers have concluded that even people who have no evident predisposition to insomnia may develop chronic insomnia through a process involving sleep system sensitization. Here’s more on what they found.
From Normal Sleep to Insomnia in Just One Year
In this prospective study, thousands of participants filled out a series of questionnaires at the start of the study and one and two years later. The Michigan researchers looked at the 262 participants who did not have insomnia at the start of the study but who, by year 1, had developed it.
These participants might be expected to have characteristics predisposing poor sleep from the start (a mother with insomnia, for example, or high sleep reactivity). But not all of them did. A total of 60 participants tested low for sleep reactivity at the start of the study (on the Ford Insomnia Response to Stress Test, or FIRST). But by year 1, these 60 people had jumped an average of 4 points on the FIRST, indicating a significant increase in sleep reactivity. Over two-thirds went from low sleep reactivity to very high sleep reactivity following major life stress and the onset of insomnia in the space of just one year. At year 2, the high sleep reactivity persisted regardless of whether their insomnia was chronic or not.
A Different Path to Chronic Insomnia
In a nutshell, here’s the take-away:
- People with apparently low vulnerability to insomnia (like the person described at the beginning of this blog post) can develop high sleep reactivity in conjunction with major life stress and an episode of insomnia.
- Stress exposure leading up to insomnia appears to sensitize the sleep system. This lends support to the idea that insomnia itself may be a perpetuating factor in chronic insomnia. Every episode may trigger neurobiological changes that increase the risk of subsequent bouts of insomnia, just as every experience of depression increases the risk of future depression.
- High sleep reactivity, once it develops, is persistent.
No matter how or why your insomnia develops, don’t wait to look for help. Take action right away.