To determine the effect of a powdered skim milk product iNdream3; (Synlait Milk Ltd) on sleep in subjects with insomnia. A 9 week double blind randomized placebo controlled crossover trial was conducted in adults with primary insomnia (mean age 40 +/- 14 years, 14/19 female, insomnia severity index >15,). Subjects were randomized to Product A: iNdream3 'NightMilk' and Product B: 'DayMilk' for 3 weeks each with a 1 week washout. Total sleep time (TST), sleep efficiency (SE), sleep onset latency (SOL) and sleep quality were measured both subjectively (sleep diary and questionnaires) and objectively (actigraphy), over 1 week during baseline and active treatment arms. At the end of each arm subjects underwent home polysomnography (PSG). Consuming NightMilk compared with DayMilk improved sleep symptom questionnaire scores: Pittsburg Sleep Quality Index efficiency (+5.2 vs -0.4, p = 0.039), daytime dysfunction (-0.58 vs no change, p = 0.019), sleep related disturbance (-4.3 vs -1.5, p = 0.011) and SOL from diary, (-8 min vs +5 min, p = 0.045). Percent stage N3 sleep-PSG (+8 min vs -9 min, p = 0.004) and SE- by actigraphy (+2.3 vs +0.5 %, p = 0.004) increased. The number of awakenings-actigraphy improved (-1.8/night vs +1.5/night, p = 0.003). TST was not different between treatments. In subjects with primary insomnia consuming NightMilk produced small but significant improvements in insomnia symptoms, sleep efficiency, depth of sleep but did not increase TST. The size of the effects seen was similar in magnitude to other less well designed evaluations of non-pharmacological preparations but smaller than those reported for commonly prescribed pharmaceutical hypnotic products.
