A new Brigham Young University (BYU) study of 330 young college women aged between 17 and 21, has found a link between poor quality sleep and getting less than six and a half hours of sleep—or more than eight and a half nightly hours of sleep—with higher body fat percentages. The new study also found the "sweet spot" for the amount of sleep: those who slept between 8 and 8.5 hours a night had the lowest body fat. Could this study offer clues on how to improve sleep quality?
In the new study, the participants were first assessed for body composition and asked to fill out a sleep log and they all wore an activity monitor — an accelerometer for 7 consecutive days, both day and night, which allowed the study researchers to objectively determine the quality and duration of their sleep. Women were excluded from the study if they were not able to engage in moderately intense activity, were pregnant or nursing, were dieting to lose weight, or had a known metabolic disease.
The study's conclusion was "Inconsistent sleep patterns and poor sleep efficiency are related to adiposity. Consistent sleep patterns that include sufficient sleep may be important in modifying risk of excess body fat in young adult women."
The most surprising finding of the new study, according to the researchers, was the link between bed time and wake time consistency and body weight. In particular, the study participants who went to bed and woke up at, or around the same time each day were found to have lower body fat. Those with more than 90 minutes of variation in sleep and wake time during the week were also found to have higher body fat than those with less than 60 minutes of variation. Also important was the quality of the sleep, the BYU study found that those who were able to improve sleep quality above the baseline had lower body fat.
According to BYU exercise science professor Bruce Bailey, a co-author of the study, humans all have an internal circadian clock and not going to sleep at a consistent time will mess up that clock and this in turn can influence biological activities like hormones related to satiety and activity patterns.
According to the National Sleep foundation, the timing of periods of sleepiness and wakefulness throughout the day is regulated by our internal circadian biological clocks. The circadian rhythm dips and rises at different times of the day, so adults' strongest sleep drive generally occurs between 2:00-4:00 am and in the afternoon between 1:00-3:00 pm. The sleepiness we experience during these circadian dips will be less intense if we have had enough sleep, and more intense when we are sleep deprived.
The body's biological clock or (circadian rhythm) can also be affected by light or darkness, which can make the body think it is time to sleep or wake up. Body clock sleep problems have been linked to a hormone called melatonin. Light and dark will affect how the body makes melatonin. Most melatonin is made at night. During the day, light tells the body to make less melatonin.
Melatonin is a hormone secreted by the pineal gland in the brain and it helps regulate other hormones and maintains the body's circadian rhythm. Being exposed to bright lights in the evening or too little light during the day can disrupt the body's normal melatonin cycles. For example, jet lag, shift work, and poor vision can disrupt melatonin cycles.
Our quality of sleep that we get every night can also be influenced by how much stress we are experiencing day to day. The neuroendometabolic (NEM) stress response is responsible for how our body deals with stress. One of the key responses is the neuro-affective response which is made up of the brain, gut and autonomic nervous system. When stress is increased you can often find people presenting complaints of insomnia. When the body is experience stress that it can no longer regulate or manage, the NEM’s complex becomes overburdened and can result in dysregulation of the neuro-affective circuit. It is essential that the triad between the gut, brain and autonomic system be kept in balance as it can lead to decapitating symptoms such as sleep maintenance insomnia and sleep onset insomnia. When you are experiencing symptoms such as these and feel like you are experiencing stress that is encumbering yourself, it may be beneficial to give yourself time to relax and recover. Reducing stress may be the most effctive way to improve sleep quality.
