Naz Perween Alam and Kedar Prasad Sinha

Ethanol and nicotine are the two most widely used and abused substances in the world and are often consumed together. However, the effects of chronic co-consumption of ethanol and nicotine as well as their withdrawal on sleep-wakefulness remain poorly understood. We examined effects of chronic treatments of rats with ethanol, nicotine, and ethanol + nicotine and their withdrawals on sleep-wake architecture. Saline, ethanol (3g/kg), nicotine (3mg/kg), or their mixture was injected intraperitoneally at early light-on phase for 28 days in four different group of rats. Sleep-wake parameters were recorded for 6 hours on treatment day-1, day-14, and day-28, followed by one day without any treatment (day-29 or withdrawal day). The findings suggest that while ethanol acutely increased sleep, its chronic use produced only marginal effects as rats developed a tolerance for ethanol. However, sleep decreased severely on withdrawal day. Nicotine acutely suppressed sleep, but like ethanol, rats developed tolerance and nicotine’s effectiveness was attenuated with its chronic use. Sleep, especially, REM sleep, however, increased significantly on withdrawal day. When given together, ethanol and nicotine nullified each other’s effects on sleep-wake parameters. These findings are discussed in the light of known interactions between ethanol and nicotine in influencing sleep.

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