That proposition fell by the wayside long ago—yet new evidence suggests that the timing of meals does affect our sleep. Particularly in people prone to insomnia, eating regular meals, and eating dinner earlier in the evening, may be important keys to sounder sleep and good health.
Regularity is a familiar theme to people with insomnia. “Go to bed and get up at the same time every day,” we hear again and again.
Good sleepers tend to do this naturally. Their stable, high quality sleep is a sign that their internal circadian rhythms are all synched up. These rhythms are established by the body clock, which hews to a 24-hour cycle with daily exposure to sunlight.
People with insomnia are not so regular about sleep. Over a two-week period, the authors of a study of daily activities and sleep found, insomnia subjects had over an hour of daily variability in when they went to bed and got up in the morning. This variability could throw their internal rhythms out of whack and lead to symptoms of insomnia.
But compared with normal sleepers, the insomniacs were also more variable in when they had meals and snacks. For them, lunch could vary by as many as 3 hours from one day to the next. The timing of their evening snacks had a range of almost 3 hours as well.
A Relationship between Eating and Sleeping
Sunlight is not the only thing that keeps our circadian rhythms synched up. In addition to the master clock in the brain, which is set by the sun, many peripheral clocks are spread throughout our bodies. Some of them are sensitive to the timing of meals. Eating at odd hours disrupts their rhythm. Circadian rhythms are then thrown out of sync, and this invites insomnia.
“This finding highlights the potential importance of regular mealtimes,” the authors state. “Perhaps incorporating a regular meal schedule into treatment for those with insomnia could help to align the internal clock with a 24-hour light/dark cycle, which would contribute to healthier sleep.”
Avoid Iron-Rich Foods at Night
Another study suggests that eating foods high in iron at night is harmful to health. Not only does it alter circadian rhythms, but it may also increase our vulnerability to obesity, diabetes and other metabolic disorders.
This study was conducted on mice. One of the many peripheral clocks in mice and humans is located in the liver, an organ that regulates blood glucose levels. In this study, scientists found that dietary iron establishes the circadian rhythm of the liver.
Eating iron-rich foods during the daytime is healthy. Metabolic processes that ensue after a meal high in meat, beans, leafy green vegetables or dried fruit are not harmful when they occur in sync with the body’s natural rhythms.
But feeding iron to mice at a time when they would normally be asleep resulted in the clock in the liver going out of sync with the body clock in the brain, and a dysregulation of blood glucose levels. Particularly in shift workers, said investigators in ScienceDaily, eating foods high in iron at night could lead to obesity, diabetes and other metabolic disorders.
So if you’re a poor sleeper or prone to raiding the fridge at midnight, aim for regular meals and lighter midnight snacks.
What foods do you typically eat when you can’t sleep?