Nicole Pagel '15 Integrated Health Sciences Major
The Effect of Caffeine on Mood and Memory in Females Getting ≤ 6 or ≥ 8 Hours of Sleep
Sleep deprivation is one of the top five threats to academic achievement. Unfortunately, college students often lack adequate quantity and quality of sleep. Many students use caffeinated beverages as a stimulant source in an attempt to make up for their lack of sleep.
PURPOSE: to determine whether caffeine can compensate for a lack of sleep regarding mood and memory in students getting either ≤ 6 or ≥ 8 hours of sleep per night.
METHODS: Institutional Review Board approval was obtained. A sleep questionnaire, linked to a recruitment email, was sent to sophomore, junior, and senior females at the college (n=57). Habitual sleep patterns were used to assign participants to one of two groups, ≤ 6 hours (N=12) or ≥ 8 hours (N=15). Exclusion criteria were smoking, medications (excluding birth control), and caffeine sensitivity. Subjects read and signed an informed consent before participating in the study. Subjects consumed a flavored beverage in two trials, once with caffeine (200 mg) and once without, in a double-blind crossover design. Working memory was assessed by a word recall task. Mood was assessed by a self-reported mood questionnaire, which contained six positive and six negative symptoms. A 2 X 2 mixed ANOVA through SPSS was used to analyze the data. Correlation coefficients were used to analyze sleep patterns and GPA.
RESULTS: The mean number of words recalled increased by 3% with caffeine treatment in the group sleeping ≤ 6 hours and by 8% in the group sleeping ≥ 8 hours (p=0.081). Positive mood scores increased by 2.3% with caffeine treatment in the group sleeping ≤ 6 hours and by 17.7% in the group sleeping ≥ 8 hours (p=0.011), with a statistically significant interaction between the sleep group and treatment (p=0.042). Negative mood scores decreased by 10.3% with caffeine treatment in the group sleeping ≤ 6 hours and by 2.9% in the group sleeping ≥ 8 hours (p=0.03).
CONCLUSION: Caffeine improved mood and memory in both groups, but was less effective in the group lacking adequate sleep. Therefore, caffeine cannot completely compensate for a lack of sleep as maximal improvement was achieved by the group obtaining ≥ 8 hours of sleep per night.
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