But did you know that working night shifts, third shift (“graveyard shift”), early morning shifts, or rotating shifts can also affect your hormone and hunger levels, causing you to gain weight?
Why Is Shift Work So Hard on the Body?
Before discussing the hormones and weight gain, it’s important to understand how shift work affects your body’s ability to sleep.
The body’s natural sleep/wake homeostasis (tendency toward equilibrium) tells you when your biological need to sleep has accumulated to the point where sleep must happen soon to offset how long you’ve been awake. Your circadian rhythm (body clock) modulates that powerful sleep drive by regulating periods of sleepiness and alertness throughout the day.
When your sleep schedule is rearranged, your circadian rhythm can go awry, similar to how you’d experience jet lag when flying across time zones. Without a properly working body clock, you might want to fall asleep as soon as the sun goes down (an urge you fight off with caffeine). You may also find yourself powerfully alert when you know you need to be catching up on rest (which may lead you to take supplements or sleep aids).
How long you sleep, and the patterns and quality of your sleep, can be negatively affected by the changes to your sleep/wake schedule. This can lead to side effects like drowsiness, hunger fluctuations, and in the long term, health issues that are linked directly to the quality and quantity of your sleep. (For example, cardiovascular issues, memory impairment, or even brain damage.)
Of course, not every shift worker will have these problems. Some who work alternate shifts adapt better than others. For example, if you’re a night owl by nature and you work a late night shift, you may not notice a dramatic difference in your sleep or eating behaviors. Conversely, if you’re a morning lark (early riser) who reports to work at 6:00 A.M., you may not have any issues at all.
However, when looking at the opposite of these scenarios you’re likely to see a problem. Night owls accustomed to a bedtime of 2:00 or 3:00 A.M. will not find early morning shifts an easy adjustment. Early risers who naturally awaken at 6:00 A.M. may find staying awake for a graveyard shift to be grueling.
Shift Work, Your Body Clock, and Your Sleep Drive
Changing your wake time, sleep time, nap time, and meal times can throw your body into a state of confusion. Suddenly your needs to sleep and eat come into direct conflict with your body’s natural urges to synchronize activities with the sun. These urges are difficult to contradict because they’re part of the human body’s internal biological clock, which dictates the timing of your sleepiness, wakefulness, and yes, hunger.
Circadian rhythm is controlled by a group of cells in the brain’s hypothalamus. These cells are also responsible for sending signals to the brain regarding hormone levels, body temperature, and other functions that affect sleep.
The direct line between the eye and the body clock means you’re wired to respond to the movements of the
sun; light means wake up, dark means go to sleep. Sleep hormones are tied to this cycle and are released by the brain in response to daylight. Darkness signals the brain to release melatonin. Melatonin triggers drowsiness, ushering you into sleep. When the sun rises in the morning, the brain suppresses melatonin production, allowing you to wake up and feel alert again.
Thus, most people’s body clock schedules look like this:
- Wake in the morning with the daylight, hungry.
- Feel energetic throughout the morning (assuming you’ve slept enough.)
- Get hungry mid-day.
- Feel sleepy between 1:00 and 3:00 P.M.
- Get hungry and eat in the evening.
- Feel sleepy again after the sun goes down, with the most powerful sleep drive occurring between 2:00 and 4:00 A.M. (by which point you’d be in a deep sleep, having gone to bed sometime between sundown and midnight).
This schedule can vary slightly depending on whether you are a morning person or a night owl. However, some version of this is every human’s default setting.
Shift Work Sleep Disorder
If shift work disturbs your sleep patterns, preventing you from getting enough sleep, you may have a circadian rhythm sleep disorder called shift work sleep disorder (SWSD). People with SWSD often get 4 to 5 hours of sleep every 24 hours, whereas the recommended amount of daily sleep for adults is 7 to 9 hours.
This sleep deprivation can manifest in an inability to sleep, premature awakenings (waking up earlier than you want to and being unable to go back to sleep), and fragmented, poor quality sleep.
Though you don’t have to have SWSD in order to have hunger and hormone problems, these problems usually are linked.
Hormones, Hunger, and Nighttime Eating
Sleeping enough every day — and getting uninterrupted, high-quality sleep — is a critical component of staying healthy. Sleep puts the body into repair mode, allowing a variety of biological functions to take place, including hormone regulation and the conversion of food into energy.
If you’re chronically sleep deprived, these processes can’t perform optimally. And unfortunately, people with shift worker sleep disorder are sleep-deprived, getting significantly less sleep than they need on a daily basis.
One of the many functions negatively impacted by sleep deprivation is the regulation of the appetite hormones ghrelin and leptin. Ghrelin activates hunger; leptin suppresses it. When you’re sleep deprived, your levels of leptin decrease and ghrelin increase, making you hungry. On top of that, you’re exhausted.
When you’re famished and tired, you’re more likely to reach for high-carbohydrate, high-sugar snacks to fuel you through the energy lull. You’ll probably also reach for salt and fat, since your body needs these to send the “I’m full” signals to the brain.
Because your hunger hormones are at the wrong levels due to lack of sleep, you’re likely to overeat all of these fatty, high-calorie foods, consuming larger or more frequent portions than you would when you’re rested. Unless you have a miraculously fast metabolism, this inevitably leads to weight gain.
A second sleep-related issue affecting weight is your level of glucose (blood sugar). Not sleeping enough can harm your cells’ ability to make glucose into fuel. Too much free-floating, unused glucose in your system can lead to insulin resistance — a buildup of glucose in the bloodstream that can lead to Type 2 diabetes.
Studies also show that just a few nights of poor sleep can also lead to a substantial increase in fatty acids levels, a known precursor to pre-diabetes. Being sleep deprived raises the levels of the stress hormone cortisoltoo, which places you at a higher risk for diabetes and obesity.
Many of these metabolic changes have been observed in people who experience just a few nights of poor sleep. Imagine what happens if you go without enough sleep for weeks, months, or even years with SWSD.
You don’t need to imagine it, because we have the data: individuals who sleep less than 5 or 6 hours per 24-hour period are twice as likely to develop diabetes. They’re also at an increased risk of high cholesterol, high blood pressure, heart disease, and many other serious conditions.
Sleep and Overeating: The Vicious Cycle
Unfortunately, not getting enough sleep and overeating go together, creating a vicious cycle. If you don’t sleep well, the next day you’re likely to eat a lot more calories, more fat, and more sugar — maybe up to 550 more calories, according to one Mayo Clinic study.
Research also shows that those poor food choices made during the day affect the quality of your sleep later that night. Eating unhealthily can increase how long it takes you to fall asleep. High-sugar foods can also trigger fluctuations in your blood sugar while you’re asleep, and these spikes and dips can wake you up.
Getting a poor night’s rest a second night in a row will keep the cycle going; exhausted, moody, with your appetite hormones out of balance, you’re more likely to overeat and consume sugar and caffeine to power yourself through your day. And so the cycle continues, with you gaining on weight (and a greater risk of diseases) in the process.
Shift work disorder is no joke: the stress of an unusual work shift can pose serious risks to your health. Learning strategies for sleeping better and coping with the change can go a long way towards boosting your wellness.
Sound Sleep Health is hosting an education presentation on the Sleep-Nutriton Connection March 23, 2017 at their Kirkland office from 6pm-7pm. For more info just click here!