Sleep deprivation has a strong negative effect on labour market performance, according to research by Joan Costa-Font and Sarah Flèche of the Centre for Economic Performance at the London School of Economics.
Their study, to be presented at the Royal Economic Society''s annual conference at the University of Bristol in April 2017, analyses data on a representative sample of children born in and around Bristol in the early 1990s – the Avon Longitudinal Study of Parents and Children, known among respondents and their parents as ''Children of the 90s''.
The researchers find that when parents get less sleep because they are woken by their babies, they are less likely to work, work shorter hours and earn less. The effect of sleep disruption caused by children is particularly strong for low-skilled mothers, but has less impact on fathers.
Nevertheless, the authors point out, we are all sleeping less on average, and so the population as a whole may suffer the economic impact of sleep deprivation. They conclude: ''Sleep is a major determinant of employment outcomes that needs more attention. The number of hours the average person sleeps has declined over the past century, and we still ignore its effects on economic activity and economic performance.''
Sleep matters
Lack of sleep is responsible for human fatigue, and can undermine economic performance. Paradoxically, the extent to which sleep time is a productive activity or not, has received very limited attention in economics research so far. Sleep is often overlooked in economics models despite its obvious restorative effects on human health alongside its influence on brain plasticity and feelings of wellbeing.
Sleep exerts an influence on emotional wellbeing and restful perceptions, and sleep deprivation more generally, even when moderate, is found to be detrimental to employment behaviours. The number of hours the average person sleeps has declined over the past century, and we still ignore its effects on economic activity and economic performance.
Children''s sleep as an experiment
Although sleep deprivation can have several triggers such as round-the-clock access to technology, time and work schedules alongside changes in light and noise, there is evidence of household derived sleep deprivation.
Specifically, sleep deprivation resulting from children''s sleep routines together with increasing parental involvement and parental sharing in child bearing duties makes child related sleep deprivation a potential source of variation in adult sleep. This is especially the case when we control for other controls including parental coordination efficiency.
Our data: the Avon Longitudinal Study of Parents and Children (ALSPAC)
We rely on a unique dataset for the UK, a cohort study that follows a sample of 14,000 families from a child''s birth to age 25. More specifically, it contains records of mothers since pregnancy and, crucially for our paper, has the advantage of including a rich and validated set of measures of both parental and child sleep alongside a set of other variables to be employed as controls and employment outcomes. For example, it contains very precise information on the child''s quality of sleep, including whether the child wakes up at night, sleep time and day sleep, as well as child sleeping routines and environmental triggers of sleep quality.
We can then relate these measures to objective and subjective measures of parental sleep quality, including average sleep duration, and whether the mother/father feels she had enough sleep. Another advantage is that the data provides us with information on both maternal and paternal employment characteristics, including employment status, the number of hours worked, job satisfaction and income for parents on a longitudinal basis.
Findings
Figures 1 and 2 display the association between two employment outcomes (both the probability of mother''s employment and her household income) on the number of times the child wakes up at night for a sample of 10,000 children (see below for data details). In both cases, the Figures show a strong negative relationship.
Consistently, our main finding confirms that the relationship between sleep and employment outcomes works through the channels we consider: (i) child sleep quality is a major driver of parental sleep quality; and (ii) parental sleep quality is strongly correlated with parental employment and working-time decisions.
Our two-stage least squares estimates of the effect of parental sleep on economic performance are substantial. We find that improving the mother''s average nightly sleep duration by one hour increases employment by 4 percentage points, the number of hours worked by 7%, household income by 10-11% and job satisfaction by 0.01 points.
So what?
Sleep is a major determinant of employment outcomes that needs attention in designing employment policies. The estimated effect of sleep in our study can be attributed to changes in child sleep quality.
To our knowledge, this is the first paper that finds a link between child sleep quality and parental economic performance. The average effects mask substantial heterogeneity: fathers are somewhat less affected by child sleep problems; similarly, the probability of high-skilled mothers working is not affected when children wake up at night. Low-skilled mothers instead experience a large decrease in employment and the number of hours worked when facing sleep deprivation.
