The small study found that the time of day that people eat may impact mood and mental health. However, the results may indicate more about a disrupted circadian rhythm than meal timing.
The research enrolled 12 men and seven women in a randomized, controlled study. They underwent a “forced desynchrony” to throw off circadian rhythm, ultimately mimicking what somebody who performs shift work, experiencing jet lag, or some other circadian rhythm disruption may go through. They did this by using dim lights to create four 28-hour “days.”
By the fourth “day,” participants’ behavioral cycles were inverted by 12 hours to simulate night work, meaning they ate at night and slept during the day. They were then randomly assigned to one of two meal timing groups.
A control group ate meals on a 28-hour cycle, so they were eating during both night and day. The daytime-only meal group ate on a 24-hour cycle and as the name implies, only during the day.
The daytime-only group showed no mood changes, while those with the circadian disruptions and night meals had more mood changes.
Once again, the changes here may come down more to a variety of factors associated with an unnatural sleep/wake cycle instead of just meal timing.
But that doesn’t mean that meal timing and mood are completely separate. When you eat can play a role in how you feel in a couple of ways.
One is that going too long in between meals can create feelings of irritability and anxiety. When you go longer than four hours without eating, your blood sugar can drop, leading to the feelings mentioned above. Having a snack can usually tame it.
Further, eating too late in the evening can signal to your body that it is not time for sleep, thus throwing off your sleep/wake cycle and making it more difficult to fall asleep. Trouble falling and staying asleep can impact mood and mental health.
Try to get your food during the day, optimally starting your day with a big meal, then gradually eating smaller amounts as the day progresses. Avoid food within a few hours of bedtime, and if you eat, make it light.