Methamphetamine self-administration by humans subjected to abrupt shift and sleep schedule changes.
BACKGROUND
Methamphetamine attenuates disruptions that occur after changes in work shifts. The reinforcing effects of the drug during shift work have yet to be characterized.


OBJECTIVE
This study examined methamphetamine-related mood, performance, and reinforcing effects during simulated shift work.


METHODS
Ten volunteers (four women and six men) completed this 19-day study. Participants were given an opportunity to self-administer oral methamphetamine (10 mg) or receive a $1 voucher before and after an 8-h work period for four consecutive days under two shift conditions: (1) "day shift" in which they went to bed at 2400 hours and woke up at 0800 hours and (2) "night shift" when they went to bed at 1600 hours and woke up at 2400 hours. Thus, participants completed task batteries either from 0815 to 1715 hours or from 0015 to 0915 hours. Shift conditions alternated three times during the study and were separated by an "off" day.


RESULTS
Night-shift work disrupted psychomotor task performance and some ratings of mood, especially on the first night. Consistent with this, participants chose to take methamphetamine significantly more often on the first night-shift night compared with the first day-shift day. Regardless of shift condition, however, participants selected markedly more methamphetamine doses before the work period than after it (73% versus 34%).


CONCLUSIONS
These data show that methamphetamine self-administration occurred more often before work rather than after work, suggesting that the use of stimulants by shift workers may be one strategy employed to meet behavioral demands especially under conditions engendering poor performance, fatigue, and/or sleep disruptions.
Kirkpatrick
Matthew G
MG
Department of Psychology, Columbia University, New York, USA.
Haney
Margaret
M
Vosburg
Suzanne K
SK
Comer
Sandra D
SD
Foltin
Richard W
RW
Hart
Carl L
CL
D000328:Adult; D000339:Affect / Q000187:drug effects*; D000697:Central Nervous System Stimulants / Q000494:pharmacology* / Q000627:therapeutic use; D002755:Choice Behavior; D004305:Dose-Response Relationship, Drug; D005221:Fatigue; D005260:Female; D006801:Humans; D008297:Male; D008694:Methamphetamine / Q000494:pharmacology* / Q000627:therapeutic use; D011597:Psychomotor Performance / Q000187:drug effects*; D012646:Self Administration; D020178:Sleep Disorders, Circadian Rhythm / Q000188:drug therapy / Q000523:psychology*; D014851:Wakefulness; D014940:Work Schedule Tolerance
D000697:Central Nervous System Stimulants; D008694:Methamphetamine