Our Biological ClockHuman beings have an internal biological clock that follows circadian rhythms, naturally synchronizing with the earth’s rotation. When the sun comes up, we wake up, our metabolisms speed up and we become active. After the sun goes down, our metabolisms slow down. We take time to rest and relax and finally fall asleep. If we follow the circadian rhythms, we are hungrier during the day and taper off our food intake at night.
According to senior author Phyllis Zee, M.D., the study revealed that when "sleep and eating are not aligned with the body’s internal clock, it can lead to changes in appetite and metabolism, which could lead to weight gain.” The 23 late sleepers included in the study showed significantly different eating habits than those of the 28 normal sleepers:
Normal sleepers consumed 248 less calories per day on average than the late sleepers. Also:
- Normal sleepers ate twice as many healthy fruits and vegetables as late sleepers and half as much fast food. They also consumed far fewer full calorie soft drinks.
- Normal sleepers ate a final snack at 8:30 p.m. and retired by 12: 45 a.m., while the “night owls” ate a final full meal at 10 p.m. and didn’t go to sleep until 3:45 a.m.
- Normal sleepers had a lower, healthier body mass index (a body weight measurement) than late sleepers.