Objective: 

Water-soluble folate is needed for the synthesis of serotonin and melatonin, which are neurotransmitters influencing sleep. However, knowledge about the association between intake of folate and sleep is limited.

Methods: 

Ten healthy volunteers (7 females, 22–40 years, BMI mean 22.6 range 20.0–27.3 kg/m2) participated in a pilot study consisting of three separate sessions. Actual sleep time (h:min) and efficiency (% of sleep of total time spent in bed) were measured by Actiwatch AW7 (CamNtech, Cambridge, UK). Folate intake was assessed by 24 h food dairy and calculated using the Diet32 (Aivo Finland OYY, Finland) software. Validated Karolinska sleepiness scale (KSS) was used to evaluate subjective tiredness. Generalized estimating equations method was used to study the association between intake of folate (higher vs. lower) and sleep variables.

Results: 

Sleep time varied between 4.5 – 8.1 h and efficiency 79.8–96.2%. Mean intake of folate was 359 mg (95% Cl 249–469). If intake exceeded median (293 mg), subjects slept longer (mean 7.8 95% Cl7.2–8.3 vs. 7.4 95% Cl 6.9–7.9, p=0.017) and more efficiently (mean 90.6 95% Cl 87.7–93.4 vs. 88.5 95% Cl 85.5–91.4, p<0.001). Sleep time lengthened also if intake of folate was energy standardized (mean 6.5 95% Cl 5.9–7.0 vs. 6.2 95% Cl 5.6–6.8, p=0.033). Those receiving more folate slept about 22 min (95% Cl 4–41) longer. Neither absolute nor energy standardized intake of folate was associated with subjective tiredness measured by KSS.

Conclusion: 

Absolute and energy standardized intake of folate associated positively with total sleep time and absolute intake also with sleep efficiency. Intake of folate had no influence on subjective feeling of vigor in the next morning.