The ChronoFast trial found that restricting meals to between 8 a.m. and 4 p.m. was associated with improvements in several objectively measured aspects of sleep compared with participants' usual eating patterns.
The same benefits were not seen when participants ate between 1 p.m. and 9 p.m.
However, the researchers cautioned that the study involved just 31 women, all aged 53 to 65, and the results need to be confirmed in larger and more diverse groups.
'The later they eat, the worse they sleep'
Patrycja Paradowska, a clinical dietitian who specializes in the psychological aspects of eating, said the findings were consistent with what she sees in patients.
"I see a direct relationship between food, its quality and quantity, meal times and patients’ sleep," she said. "The later they eat, the worse they sleep."
In the randomized crossover study, all participants followed both eight-hour eating schedules for two weeks, with a break between the two periods.
Their calorie intake, diet composition and physical activity were kept broadly unchanged.
Sleep was assessed using questionnaires and actigraphy, in which a wrist-worn device monitors movement to estimate sleep and waking patterns.
The devices recorded improvements during the earlier eating schedule in measures including sleep efficiency, sleep fragmentation and the duration of nighttime awakenings.
The researchers did not, however, find significant differences between the two eating schedules when comparing changes overall.
Participants also reported no significant improvement in their own perception of sleep quality, including through the Pittsburgh Sleep Quality Index, a widely used questionnaire assessing factors such as sleep duration, disturbances and use of sleeping medication.
Paradowska said the small and highly specific group of participants was an important limitation.
Still, she said shifting meals earlier was a relatively simple change that many people could test for themselves.
She stressed that 4 p.m. should not be treated as a universal cutoff. Someone who begins the day at 10 a.m. and goes to bed after midnight would naturally have a later eating schedule.
More important, she said, may be the interval between the last meal and bedtime.
"I personally recommend that patients leave three to four hours between eating and going to bed," Paradowska said.
That interval may be particularly useful for people with acid reflux or other digestive problems, because even a light meal shortly before lying down can aggravate gastrointestinal symptoms.
The relationship also appears to work in the opposite direction. Poor sleep can make healthy eating more difficult, Paradowska said, with sleep-deprived people often eating larger meals and consuming more calories.
The researchers said further studies are needed to determine whether the sleep effects seen in ChronoFast also occur in men, younger people and other population groups.
(rt/gs)
Source: zdrowie.pap.pl