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Introduction: The interaction between sleep and biomarkers of immune functioning (e.g., altered cytokine profiles) has been shown previously. The aim of this study was to investigate the relationship between perceived immune functioning and sleep in healthy young adults. Methods: Students of different Dutch universities participated in an online survey. Subscales of the SLEEP-50 questionnaire were completed to assess narcolepsy, insomnia, and circadian rhythm disorder (CRD). Total Sleep Time (TST), sleep quality, and number of nightly awakenings were assessed as well. Perceived immune functioning was assessed with the Immune function questionnaire (IFQ), and rated on a scale ranging from 0 (very poor) to 10 (excellent). Associations between sleep outcomes were related to perceived immune functioning using nonparametric Spearman correlations. Results: A total of 2489 healthy students (16.8% men) completed the survey. Their mean (SD) age was 21.2 (2.1) years old. Perceived immune functioning, as assessed with the IFQ, correlated significantly with scores of insomnia (r = 0.282, p = 0.000), narcolepsy (r = 0.229, p = 0.000), and CRD (r = 0.166, p = 0.000). In line, perceived immune functioning assessed with the 1-item rating also correlated significantly with scores of insomnia (r = -0.193, p = 0.000), narcolepsy (r = -0.135, p = 0.000), and CRD (r = -0.136, p = 0.000). TST did not correlate significantly with perceived immune functioning. The number of nightly awakenings correlated significantly with both the IFQ score (r = 0.185, p = 0.000), and the 1-item perceived immune functioning rating (r = -0.108, p = 0.000). Significant associations were also found between sleep quality and both the IFQ score (r = -0.209, p = 0.000) and 1-item perceived immune functioning rating (r = 0.199, p = 0.000). Conclusion: Significant associations were observed between perceived immune functioning and various sleep parameters. These results confirm previous findings of a bi-directional relationship between sleep and immune functioning, and suggest that a healthy immune status may contribute to improved sleep, and vice versa.

To evaluate the next-morning residual effects of ramelteon (8 mg), zopiclone (7.5 mg), and placebo on driving performance, memory functioning, psychomotor performance, and mood in healthy adult subjects following bedtime dosing and a middle of the night awakening.Single-center, randomized, double-blind, double-dummy, placebo-controlled, crossover study.Utrecht University, The Netherlands.30 healthy volunteers (15 males and 15 females).a single dose of ramelteon (8 mg), zopiclone (7.5 mg), and placebo, administered at bedtime.A balance test was performed at night. Other tests were performed the following morning, 8.5 h after administration. Subjects performed a 100-km highway driving test in normal traffic. Primary outcome measure was the standard deviation of the lateral position (SDLP), i.e., the weaving of the car. After driving, cognitive, memory, and psychomotor tests were performed and mood was assessed.SDLP was significantly increased after the intake of ramelteon (+2.2 cm) and zopiclone (+2.9 cm). Ramelteon and zopiclone produced significant impairment on reaction time (P0.024) in the Sternberg Memory Scanning Test, slow (P0.007) and fast (P0.010) tracking, reaction speed (P0.015) and tracking (P0.001) in the Divided Attention Test, and delayed recall (P0.032) in the Word Learning Test. In contrast to ramelteon, zopiclone additionally impaired performance on the Digit Symbol Substitution Test (P0.001) and the balance test (P0.001).Ramelteon (8 mg) and zopiclone (7.5 mg) significantly impaired driving performance, cognitive, memory, and psychomotor performance the morning following bedtime administration. In contrast to zopiclone, ramelteon produced no balance impairments. CLINICAL TRIAL IDENTIFIER: NCT00319215 (www.clinicaltrials.gov).