There is an undeniable association between stress and sleepless nights. Most people have first hand experience of this but what is less clear is whether the stress we experience in early life has an effect on sleep later in life. Alice M. Gregory and Nicola L. Barclay, two British psychologists, have attempted to answer this question by reviewing literature from a variety of studies.
One source of material came from the Dunedin study. This is a long running study of 1037 people born in Dunedin, New Zealand, between 1st April 1972 and 31st March 1973. Testing began at the age of five and then approximately two yearly until the age of 15. From then on the intervals between tests increased somewhat. The most recent test, age 32, involved interviews, physical and dental tests, blood tests and a variety of surveys about health and psychosocial functioning. The next test will be undertaken at age 38. What the stress/sleep investigation found was that children who grew up in families of high conflict (that is where three or more assessments had been undertaken) were more likely not to report sleep disturbances from the age of 18. Statistically this meant only 23 per cent of the sample reported insomnia at age 18.
Other studies have demonstrated a link between childhood sexual abuse and sleep disturbance during adulthood. Another study found that 46 per cent of the sample who reported moderate to severe adverse childhood experiences were more active during the night and experienced more awakenings. The authors point out that despite these compelling findings there is a relative scarcity of research looking into the links between stress and insomnia.
Stress in itself is a complex issue and other factors have to be considered before we can settle on a simple assumption that early-life stress is the cause of later-life insomnia. This is something Gregory and Barclay highlight in their article. They suggest the likelihood of multiple pathways by which stress and sleep problems are linked. In one example they point to the very strong possibility that high stress families may be less likely to establish set bedtimes for children and/or reduce noise and light levels to help promote a restful sleep. They also point to the vulnerability that comes with sleeping. In order to sleep we have to ‘let go' of vigilance and this can be difficult in a house of high tension and arguments.
Our physiology also responds to stress in ways that can affect sleep. For example a conditioned fear response is associated with increased activity of an area of the brain known as the amygdala. The amygdala has an important role in emotions and is thought, amongst other things, to be implicated in depression.
There appear to be indications that early life stress can have an influence on later life sleep but the jury is still out until more research is undertaken. Rather than spend time on such a complex path a more fruitful line of enquiry might be to examine the nature of differences in children. Why do some children appear to be more robust and resilient when exposed to stress yet others are not?