According to a recent study, people who sleep late are more likely to be overweight than people who go to bed before 11 pm. This is probably because ‘late sleepers’ are more likely to graze on high-calorie snacks throughout the evening.
However, the issue runs deeper than this. ‘Late sleepers’ are also more likely to wake up throughout the night, so they get less restorative sleep. As a result, their hormones, metabolism, and mood suffer – making weight gain a real possibility.
When it comes to weight loss, your sleep schedule is just as crucial as your diet plan and exercise regime. With that in mind, let’s explore the complex relationship between sleep and body mass index (BMI).
Why Does Staying Up Late Make You Fat?
If you want to prevent weight gain, it’s essential to get the right amount of sleep. Most people require 6-8 hours of sleep per night to stay healthy. Too little and too much sleep is associated with being overweight. People that sleep too little, and people that sleep too much, often have one thing in common; they go to bed very late.
Staying up late is injurious for health because it interferes with our circadian rhythm (our 24-hour biological clock). When we stay up late, two things usually happen:
- The duration of our sleep changes (it becomes too short or too long)
- The quality of our sleep diminishes (we get less slow-wave, deep sleep)
Imagine you go to bed at around 10 pm and wake up at 6 am. Your body will be restored, your mind will be refreshed, and you’ll feel positive about the day ahead. Conversely, imagine you’ve delayed sleep until 1 am and had to get up at 6 am; you’ll wake up feeling very tired indeed. Even if you’re able to lie-in until 9 am, you’ll wake up feeling groggy and sluggish.
This is because going to bed late robs your body of good-quality ‘restorative’ sleep. If the mind and body are unable to repair themselves, staying slim will be a struggle.
What Are the Benefits of Sleep for Staying Slim?
If you regularly achieve 6-8 hours of sleep per night, you can expect the following benefits:
- Sleep Regulates Appetite – During sleep, the hormones leptin, ghrelin, and cortisol are secreted. If we sleep too little, or too much, these hormones can become imbalanced – causing us to feel hungrier than usual.
- Sleep Regulates our Mood and Emotions – Regular, good-quality sleep helps protect against stress and depression because it restores chemical processes in the brain associated with mood regulation. Generally speaking, if your mood is positive, you’re less likely to overeat, and you’re more likely to be active.
- Sleep Improves Decision Making – Lots of studies have shown that, after a good night’s sleep, we make better judgments, because we consider all of the information available to us. This is important for making healthy food choices.
- Sleep Boosts Energy Levels –The gym becomes a source of pleasure – not a chore!
- Sleep Heals Physical Complaints – Injuries, aches, and pains heal during sleep. When starting a new exercise regime, injuries are common. If you prioritize sleep after an injury, you shouldn’t need to hang up the towel for long.
- Sleep May Regulate our Metabolism – Some research suggests that sleep deprivation may lead to a weaker resting metabolic rate. In other words, sleep-deprived people may burn fewer calories at rest (during the day).
- Sleep May Protect Against Type 2 Diabetes – Diabetes is a metabolic disorder that may be influenced by sleep. Studies have shown that sleep-deprived people experience insulin resistance. If Insulin resistance goes on for an extended period of time, blood sugar becomes difficult to control, and this can lead to type 2 diabetes.
Remember, it is all about balance. Sleep could have a detrimental effect on your mood and energy levels if you sleep for more than 9 hours. Moreover. Sleep needs to be mostly undisturbed for you to get the full benefits.
So, getting to bed at a reasonable hour is vital if you want to enjoy the many health benefits of sleep. A little later, we’ll show you how to improve your sleep routine (and protect your waistline!)
Why Do We Put on Weight?
More often than not, weight gain is caused by overeating and moving too little. As we know, it’s not quite that simple, because many different factors can cause us to eat too much or move too little. For example, weight gain could be caused by:
- Mindless overeating due to boredom
- Compulsive overeating due to stress or depression
- Choosing convenience foods due to a busy lifestyle
- Choosing junk foods due to laziness
- Craving (feeling you ‘need’) energy-rich foods
- Low motivation to exercise
- Feeling too tired to exercise
- Too busy to exercise
- Unable to exercise (due to injury or other health conditions)
Incidentally, going to bed late can cause (or aggravate) many of these factors! Let’s explore this concept in a bit more detail.
How Does Sleep Affect Appetite?
At various stages of sleep, our bodies secrete the hormones leptin, ghrelin, and cortisol. These ‘appetite hormones’ determine how hungry we’ll feel the following day.
To understand the relationship between leptin and ghrelin, it’s best to think of leptin as Ying and ghrelin as Yang. Leptin is a hormone that controls our appetite and stops us from feeling hungry. Ghrelin is a hormone released in the stomach that makes us feel hungry. If our hormones are functioning correctly, we’ll crave the correct amount of food, and we’re unlikely to overeat.
According to a study on PLOS Medicine, sleeping for 5 hours or less causes ghrelin levels to increase by approximately 15% and leptin levels to decrease by 15%. As you might expect, this increases feelings of hunger, so may lead to overeating.
According to similar studies, this increase in hunger can last for up to 24 hours. Not only that, sleep-deprived individuals are more likely to crave high-fat, high-sugar foods – presumably because these foods satisfy hunger more efficiently.
Cortisol, another hormone released by the body, also has a role to play in determining how hungry we feel. When cortisol levels are high, our bodies produce less leptin (the hormone that makes us feel satiated). As such, heightened cortisol levels can cause us to feel hungrier than we really are. Cortisol levels increase when we’re stressed, overworked, and when we’ve had poor quality/short sleep.
Why Do I Pick Unhealthy Foods When I’m Tired?
It’s not only our hormones that have us reaching for the cookie tin. Studies have shown that when we get less slow-wave sleep, we make poorer judgments and decisions. When we are tired, we are less likely to be flexible in our thinking, and we find it harder to see the ‘bigger picture.’
Let’s assume it’s dinner time. You had a late night last night, and you’ve been rushing around all day trying to catch up. You’re now faced with two decisions – 1) Cook a healthy meal 2) Order a pizza.
Although a healthy meal would serve you better in the long run, you’re less likely to think about the ‘bigger picture’ when you’re tired. In fact, you’re more likely to choose the pizza because it’s the easiest option.
As mentioned, going to bed late can shorten or fragment your slow-wave sleep, so you’ll find it hard to make reasoned judgments about your diet.
Why Do I Eat More in the Evening?
Due to our 9-5 lifestyles, most of us relax during the evening hours. We’re most likely to snack during our ‘downtime.’
Watching TV and Snacking
Many people reach for snacks when they’re enjoying a passive activity such as watching television. Unfortunately, this kind of snacking is ‘mindless’ so you can quickly demolish a whole bag of chips without realizing it. Studies have shown if you sleep late, you’re more likely to snack on high-calorie junk food and sugary drinks throughout the evening.
Alcohol and Overeating
Lots of us enjoy a drink or two in the evening. In fact, many people use nightcaps to help them sleep better. The problem is, alcohol makes you crave carbs. Even if that glass of whiskey helps you fall asleep quicker, you’ll probably wake up soon after. You’ll also spend more time in REM sleep (as opposed to deep sleep) after you’ve drunk alcohol. As we know, this will negatively impact your hormones and may make you feel hungrier the next day.
Boredom and Loneliness
If you live alone (or even if you don’t), the evening can sometimes be a lonely time. You may become so bored with our surroundings that you turn to the fridge for comfort. Long winter nights can be particularly damaging for your waistline.
A Very Busy Lifestyle
Busy people often ‘forget’ to eat their lunch or dinner. If you fail to eat during the day, you’re more likely to indulge when you get home in the evening. The problem with eating when you’re already very hungry is that you’ll probably overeat. Also, as we’ll explore, eating too close to bedtime can encourage weight gain.
What Are the Problems with Sleeping Immediately After Eating?
‘No carbs after 6 pm!’ If you’ve ever tried to lose weight, you will have heard this advice. Contrary to popular belief, the body can still process food when we’re asleep (our metabolism only decreases by about 15% during sleep). Nonetheless, the body does seem to process food less efficiently during the night.
A study published by Oxford University Press found that people who had a high BMI were more likely to eat late at night (around the time their body started to produce melatonin).
The experimenters concluded that eating a meal after the body has already secreted melatonin (i.e., biological nighttime) will make it somehow harder for the body to process. It seems that, according to our circadian rhythm, our bodies are more efficient at processing food that is eaten earlier in the 24-hour cycle.
Also, eating just before bedtime can lead to indigestion and reflux. If indigestion stops you from sleeping properly, your hormones and metabolism will be affected (potentially leading to poor appetite control the following day).
If you always eat directly before you sleep, you deny your body the chance to burn fat. For example, if someone eats their last meal at 6 pm and sleeps from 10 pm until 6.30 am, they will have gone 12.5 hours without food (and will have slept for a healthy 8.5 hours). After 12 hours of fasting, the body starts to burn fat (as opposed to glycogen), so their body will have begun to burn fat.
If you always eat just before you sleep, you’d have to sleep for 12 hours to access this fat burning trick! As we know, sleeping for 12 hours is impractical and unhealthy.
What is Night Eating Syndrome?
Due to our lifestyles, many of us tend to eat more in the evenings. However, for some people, this is classed as an eating disorder – Night Eating Syndrome.
People diagnosed with this condition eat most of their food in the evening hours, either before bed or during the night when they wake up. People with this condition often eat small amounts at a time. Nonetheless, the frequency of snacks they eat throughout the evening and night can cause them to put on weight.
Night eating syndrome is often caused by emotional factors, but some people appear to be genetically predisposed to developing this condition. Some scientists have found a strong link between heightened cortisol and NES. As we know, cortisol levels can rise due to stress, anxiety, overtraining, or sleep deprivation. The symptoms of this syndrome include:
- Feeling low or depressed during the second half of the day
- Feeling out of control around food (especially in the evening)
- Feeling that you won’t be able to sleep if you don’t eat at night
- Difficulty getting to sleep and staying asleep (at least four nights per week)
- Feeling very full in the morning
Night eating syndrome should not be confused with nocturnal eating syndrome. People with nocturnal eating syndrome eat during the night but are completely unaware of their behavior. Even when they find empty food packets in their bedroom, they are often unable to recall eating this food.
If you suspect you have either of these conditions, it’s best to seek medical intervention.
Binge Eating Disorder and Sleep Deprivation
Binge Eating Disorder affects 2.8 million people in the US and is the most common eating disorder. It is defined as addictive, compulsive behavior.
People with binge eating disorder eat large amounts of food in one sitting. They will always binge in secret, and many people find more privacy during the evening hours.
There is a strong link between sleep deprivation and binge eating disorder. Moreover, people diagnosed with BED binge on more calories if they’ve had a particularly bad night’s sleep.
What does this tell us? Well, it provides further evidence to suggest that appetite and sleep are linked. Moreover, it seems to indicate that compulsive behavior gets worse when we are sleep deprived. Therefore, getting to bed at a reasonable hour seems all the more critical if you want to limit unhealthy behaviors.
Is My Lie-In Making Me Lazy?
You might think that oversleeping helps you compensate for lost sleep, but often, oversleeping impacts mood and productivity. Studies have shown that people who go to bed late and wake up late are less likely to engage in physical activity.
The worst kind of ‘oversleeping’ happens when you wake up naturally in the morning but then go back to sleep because you still feel tired. When we wake up naturally, our body provides us with a natural boost of cortisol to help us get out of bed. If we go back to sleep, we waste this natural boost of energy. When we finally wake up two or three hours later, we often feel lethargic, despite the fact we’ve slept for a long time.
Over time, sleeping-in can de-regulate our circadian rhythm and may lead to depression. So, if you want to stay active and keep your waistline in check, you should get out of bed as soon as you wake up in the morning.
Will Sleeping in the Afternoon Make Me Fat?
Napping can disrupt your circadian rhythm. Anything that deregulates your circadian rhythm could play havoc with your energy levels and make it more difficult to sleep at night.
A study published in the Journal of Clinical Sleep Medicine found that people who regularly napped during the day slept worse at night and had a higher BMI. Of course, we can’t say for sure whether the naps (and subsequent poor sleep) influenced weight gain or whether their high BMI made it harder to sleep at night (so they had to rely on daytime naps).
Nevertheless, most health professionals would advise you only to take a daytime nap if you need it because naps will probably interfere with your ability to get a good night’s sleep. People that work irregular shifts or drive long distances can use naps to increase their productivity. For the rest of us, we should focus on improving our nighttime rest if we want to keep our energy levels up.
What’s the Link Between Sleep and Diabetes?
As we’ve discussed, sleep helps to restore metabolic processes in the body. Type 2 diabetes is a metabolic disorder that occurs when the body starts to become resistant to insulin. As a result, too much glucose builds up in the blood, leading to hyperglycemia.
Some scientists predict that poor-quality sleep (in addition to diet, exercise, and genetics) could play a role in the development of type 2 diabetes.
When we are sleep deprived (i.e., less than 5.5 hours of sleep), we begin to show the signs of insulin resistance. At the first signs of insulin resistance, the pancreas usually tries to produce more insulin, to counteract the problem. Over time, this will wear the pancreas out, so it may eventually stop producing enough insulin – leading to type 2 diabetes. However, in the short term, excess insulin can cause the body to store more fat!
This suggests that even occasional sleep deprivation could cause you to gain weight more easily because you’ll (temporarily) have an excess amount of insulin in your body. Moreover, if you’re regularly getting less than 5.5 hours of sleep, you are increasing your risk of developing type 2 diabetes.
Menopause, Sleeping, and Weight Gain
Menopausal women may put on weight for a variety of reasons. For example, we know that decreased estrogen levels encourage fat to be stored on the stomach. However, weight gain during menopause is probably also caused by the sleep disruptions that occur during this time.
For example, menopausal women are more likely to experience night sweats, and nocturia (urinating throughout the night). Once they’ve woken from sleep, it can be challenging to get back to sleep. As such, many women turn to the snack cupboard for comfort.
Moreover, women are more likely to develop sleep apnea after menopause. This is partly because hormonal changes encourage muscles in the neck to relax – thereby obstructing the airways. People with sleep apnea are more likely to secrete adrenaline and cortisol during the night (due to their awakenings). As a result, this may affect their appetite, causing them to overeat the following day.
Can Sleep Help My Exercise Regimen?
Sleep is an important part of any exercise regimen. If you regularly sleep late, your fitness goals will suffer.
- Sleep aids muscle recovery – Good quality sleep encourages protein synthesis, which is vital for muscle repair.
- Sleep boosts the production of growth hormone – Growth hormone is vital for staying strong and flexible.
- Sleep improves procedural memories – If you’re trying to learn a new hobby or sport, 8 hours of sleep will help you master the skills quicker.
- Sleep Heals Injuries – You’ll be able to return to the gym quicker after an injury if you get to bed on time.
As we know, exercise is an important part of weight loss. Ultimately, being active also helps you sleep more soundly, so it works both ways. However, it’s important not to exercise too close to bedtime as this could raise your cortisol levels, making sleep more difficult.
Does Sleeping Position Affect Your Weight?
No specific sleeping position will help you lose weight. Sleeping on your side will improve circulation and may alleviate the symptoms of sleep apnea.
Moreover, it’s important to find a position that you feel very comfortable sleeping in. If you feel comfortable, you’ll fall asleep quicker, and you’re less likely to wake up throughout the night. Ultimately, this will promote restorative sleep, which is the most important thing when it comes to sleep and weight management.
The Importance of a Sleep Routine
So, as you can see, going to bed late can impact your mood, metabolism, and appetite. This is because going to bed late shortens the duration of your sleep, and makes your sleep more fragmented. Ultimately, poor sleep may lead to weight gain.
If you are trying to maintain or lose weight, take a look at your sleeping pattern. First and foremost, look at the total number of hours you are sleeping. If it is regularly less than seven then you need to make more time for sleep. Look at your schedule and allocate a new bedtime that will allow for 7-8 hours of sleep per night.
If possible, try and set your routine so that you are waking up close to sunrise. Light (and dark) are the most important cues for our circadian rhythm so try to use sunlight to your advantage. This will help to boost your energy levels, making you more likely to commit to a diet and exercise regime.
How to Sleep on Time
So, you’ve established a new (healthier) bedtime, and you’re ready to commit to it, but there’s just one problem – It’s 10 pm, and you don’t feel tired at all. Getting used to a new sleep routine can be challenging. However, the following tips should help:
- Exercise – Make sure you’re doing enough physical activity to feel tired enough for sleep. If you can’t get to sleep, start exercising moderately in the morning. This will make you feel more tired by bedtime (but won’t raise your cortisol levels unnecessarily).
- Stop using electronics near bedtime–Try to switch off all electronics two hours before bedtime. Electronics will keep your brain and body unnecessarily alert. If you feel bored, try taking a relaxing bath before bed.
- Be comfortable – Purchase some new bedding in a luxury fabric so that you look forward to going to bed.
- Sleep in the dark – Make sure your bedroom is dark at bedtime, as your body will struggle to produce enough melatonin. If your new bedtime is before sunset, consider blackout curtains or a light-blocking sleep mask to achieve darkness.
- Stop using your alarm clock – If your lifestyle allows it, try training yourself to get up at the same time every day – this will help you establish a solid sleep/wake routine. If you must rely on an alarm clock, remember not to hit the snooze button.
How to Avoid Late Night Snacking
If you want to avoid weight gain, you should avoid evening snacking as much as possible. Besides going to bed earlier, the following tips may help you avoid late-night snacking:
- Plan Your Meals – It sounds obvious but make sure you’re eating enough food throughout the day, so you’re not overly hungry at night.
- Protein – Make sure your evening meal contains an adequate amount of protein. This should help you stay fuller for longer.
- A Warming Drink – Many of us eat before bedtime because we want to consume something warm and comforting. Instead of your usual snack, opt for some herbal tea, a malty drink, or a shot of lemon and ginger juice.
- Manage Stress – As we know, stress can lead to overeating. During the evening, we often mull over the stressful events of the day. Perhaps that’s why we’re more likely to overeat before bedtime. Avoid passive ‘stress-relieving’ activities such as watching the TV. Instead, try talking to your friends or family, or engaging in something creative.
- Don’t keep sweet treats at home – Try to get into the habit of enjoying sweet treats during the daytime, when you’re outside of your home.
- Stay hydrated – ‘Hunger’ is often thirst in disguise.
Most importantly, try to distinguish emotional hunger from true hunger. If you truly feel hungry (your stomach is rumbling, and you feel weak) you should eat before bed. If you sleep very hungry, adrenaline and cortisol will rise, keeping you awake throughout the night. So, if you are very hungry, prepare yourself a light meal and chew each mouthful thoroughly to aid digestion.
How to Sleep Better If You’re Overweight
If you are overweight, it can be difficult to make yourself comfortable in bed. In particular, people with sleep apnea struggle to sleep throughout the night as their adrenaline levels rise periodically, keeping the body on high alert.
- If you can, try to sleep on your side. Side-sleeping increases circulation and can improve the symptoms of sleep apnea for many people. If side sleeping feels uncomfortable, try using a body pillow.
- If you have sleep apnea, you may snore or grind your teeth. This can keep you awake at night. To prevent this, consider sleeping with a mouthguard.
- Make sure your bedding is comfortable. If you’re regularly waking up due to night sweats, try using bamboo or linen bedding to stay cool.
- People who are overweight often have back pain. If this is the case, you may find it more comfortable to sleep with an orthopedic pillow.
Can Sleep Help You Lose Weight?
Along with a healthy diet and regular exercise, good-quality sleep can help you lose weight. When improving the quality of your sleep, be sure to consider the following factors.
- Have a regular routine (try to go to sleep and wake up at the same time each day)
- Sleep comfortably (do everything in your power to avoid nighttime disruptions)
- Sleep for 6-8 hours per night (less than 5.5 and more than 9 hours of sleep is unhealthy for most adults and may lead to weight gain).
- Go to bed at a reasonable hour (try to use the natural cues of light and darkness to your advantage)
If you put these recommendations into practice, your energy levels will increase, and your appetite will become more stable. As a result, those long, lazy evenings and midnight-munchies will become a thing of the past.
Here are some tips on how to avoid going to bed so late at night.