The Relationship between Nonstandard Work Schedule and Substance Use; New Evidence From NLSY97

Mona Khadem Sameni

University of Wisconsin Milwaukee

November 2014

The Initial Thought

The shift working neighbor who always smoked outside the building…

Nonstandard Work Schedule (Shiftwork)

Other than: Regular Monday through Friday, nine to five schedule.

U.S. Bureau of Labor Statistics (2004):

One-fifth of all employed Americans

Presser and Ward(2011):

One-third of all dual-earner couples with children

NLSY 97:

• Regular evening shift

• Regular night shift

• Shift rotates

• Split shifts

• Irregular schedule or hours

Why should we care?

Substance UseHealth hazards :

• Higher probability of accidents at work and outside work (MacDonald, Wells et al. 1999)

• Higher risk of HIV (Gorman and Carroll 2000)

• Higher probability of major depression (Libby, Orton et al. 2005).

Significant economic health costs :

• Specialty treatments

• Hospitals and emergency departments

• Homicide and insurance administration participation

• Hospitalization and premature mortality.

Why should we care? (Continued)

Efficiency and social costs

• Lower productivity of the workforce

• Higher crime rates such as drunk driving or drug possession and sale

• Dependence on various pension types

Potential Mechanisms Affecting Health

Psychosocial mechanisms :

• Related to family and social activities

(Wirtz and Nachreiner 2010); (Drake, Roehrs et al. 2004) (Llena-Nozal, Lindeboom et al. 2004) Physiological mechanisms :

• Circadian rhythms

• Sleep patterns closely related to melatonin and growth hormone levels.

(Davis, Mirick et al. 2012); (Arendt 2010); (Srivastava 2010)

Previous Literature

Job conditions Not a significant effect on drug use (Mensch and Kandel 1988)

Working night shifts + more than eight hours/ rotating shift Higher amount of alcohol use (Trinkoff and Storr 1998)

Nonstandard schedules Worse health conditions (Esp for men) (Ulker 2006)

Being a shift worker Higher odds of drinking alcohol in short-term (Dorrian and Skinner 2012)

Contributions to The Literature

First to use a US nationally representative longitudinal survey in this field.

First to investigate five separate substances. First to use survival analysis that corrects for frailty.

Is Nonstandard Work Schedule Always “Bad”?

• More free time (during the day)

• Saving existing jobs (ILO 2004)

• Helping with school

• Fewer unwanted family interactions

• Less tension and more relaxed pace

• Accommodating “night owls”.(Finn 1981)

Research Question

Do shift workers indicate higher hazard ratios for the onset of substance use compared to regular day workers?

People who held non self-employed jobs within the past year.

Data

U.S. National Longitudinal Survey of Youth, NLSY 97. Rounds 1-15 : 1997-2011

Five different categories :

• Employed not shiftwork

• Employed shiftwork

• Unemployed

• Out of the labor force

• Military Reference group : Employed not shiftwork

Data Continued

Substances :

• Alcohol

• Excessive use of alcohol (Binge Drinking)

• Cigarettes

• Marijuana

• Cocaine

Methodology

Duration framework using Cox (1972) Proportional Hazards Model.

Why duration model?

Impact of being in nonstandard work schedule on the length of time (length of spell) it takes to start using any type of previously mentioned substances.

Results of Cox (1972) : The probability of starting to use any substance given that the individual has not done so yet.

Model : (t) exp (β’x)

• Regular control variables

The Importance of Fixed Effects Estimation Besides Cox Model

Previous work in this field suffer from selection bias Fixed effects : As if there were “before and after” shift

work. Identical to DID estimation. Benefit of longitudinal data.

Survival Plots

Alcohol Binge Drinking

Cigarettes

Marijuana Cocaine

Substance Use at Different Ages

Drinkers at Different Ages Binge Drinkers at Different Ages

Smokers At Different Ages

Marijuana At Different AgesCocaine At Different Ages

Regression ResultsType of

Substance Use

Pooled OLS

Fixed Effects

Random Effects

Cox without Frailty (no

hazard rate)

Cox with frailty

correction(no hazard rate)

Alcohol

-0.003 (0.85)

-0.019(4.39)*

*

-0.012(3.09)**

-0.090(3.75)**

-0.066(2.75)**

Binge Drinking

-0.001 (2.00)*

-0.009(2.01)*

-0.009(2.13)*

-0.054(2.47)*

-0.057(2.61)**

         

Cigarettes-0.003(0.98)

-0.003(0.88)

-0.004(1.35)

-0.068(2.89)**

-0.105(4.47)**

marijuana0.004 (1.19)

-0.005(1.67)

-0.002(0.86)

-0.051(2.33)*

-0.071(3.25)**

cocaine

0.01

(5.35)**

0.004(1.85)

0.006(3.30)**

-0.015(0.68)

-0.035(1.58)

Ruling out Reverse Causality!

Shift workers use more substance or substance users do

more shift work?

Negative coefficients Less concern about upward bias.

Pooled OLS gives smaller negative or positive coefficients

Upward bias in previous literature using cross sectional

data

Conclusion

Nonstandard schedules decrease the odds of the onset of drinking and binge drinking.

Marijuana and cigarettes : Mixed results Cocaine: weakest evidence and even slightly on the

opposite direction. Social aspect of work schedule Affecting

teenagers and young adults more. Working at odd hours keeps them away from their

circle of friends and family.

Limitations and Future Work

Not every nonstandard schedule has the same effect (Data limitation)

Using a similar sample of adults seems appropriate. Application of exogenous variation methods.