Vitamin E may prevent memory deficits caused by lack of sleep

Sleep-deprived individuals who stumble through the day in a mental fog may be encouraged by the results of a new study conducted in rats. The findings suggest that daily doses of vitamin E may help prevent memory impairment caused by chronic lack of sleep.

Sleep deprivation causes oxidative stress in many regions of the brain that may, in turn, blunt our ability to learn and remember. Sleep provides the opportunity for cells to combat oxidative stress and promotes the formation of memories. We typically need a solid 7-9 hours of slumber to reap the maximum benefits. However, many of us fall short of this mark, sometimes on a daily basis, which makes us vulnerable to a slew of mental and physical health woes including poor memory.

Vitamin E is a fat-soluble antioxidant that halts the production of some harmful free radicals that can damage cells. Vitamin E exists in eight different forms: alpha-, beta-, gamma-, and delta-tocopherol; and alpha-, beta-, gamma-, and delta-tocotrienol. However, the most active form in humans is alpha-tocopherol, which is stored in the fatty tissues of the body and provides ongoing antioxidant protection.

A growing body of research indicates that the potent antioxidant properties of vitamin E may help to protect the brain, which is made up of about 60% fats. Now, a new study from the Jordan University of Science and Technology lends further support to the potential neuroprotective effects of vitamin E in the setting of chronic sleep deprivation.

To conduct the study, the researchers deprived lab rats of sleep for 6 weeks. Half of the rodents received 100 mg/kg of vitamin E per day over the 6-week period, whereas the other half did not. At the end of the 6-week period, both groups of sleep-deprived rats, as well as normal "control" rats that slept as much as they wanted, were released into a maze to evaluate their spatial learning and memory abilities. After several trial runs to learn how to navigate the maze, the animals were then tested 30 minutes, 5 hours, and 24 hours later to gauge their short- and long-term ability to remember the correct route.

Compared with the well-rested control rats, the sleep-deprived animals showed significant impairment of both short- and long-term memory in the absence of vitamin E. However, the sleep-deprived animals that received vitamin E demonstrated a preserved ability to remember the correct maze path on par with that displayed by the well-rested control rats.

Closer examination of the brains of the animals revealed that chronic sleep deprivation decreased antioxidant defense mechanisms in the absence of vitamin E, as noted by paltry levels of several antioxidant enzymes. However, sleep-deprived animals that were given daily vitamin E showed normal levels of the antioxidant enzymes, again at concentrations equivalent to those found in control mice.

Giving vitamin E to well-rested control mice did not boost their memory or further increase the levels of the tested antioxidants. Thus, the investigators believe that vitamin E protects memory but does not enhance it, suggesting that vitamin E might only work in this context if there is impairment in memory functions.

The investigators concluded that "sleep deprivation induces memory impairment, and vitamin E prevented this impairment probably through its antioxidant action in the hippocampus" of the brain.


 Source: 1. Alzoubi, K. H., O. F. Khabour, et al. (2012). "The neuroprotective effect of vitamin E on chronic sleep deprivation-induced memory impairment: the role of oxidative stress." Behav Brain Res 226(1): 205-210.