Deep Dive

SLEEP CYCLES

During your sleep, your muscles are repaired, your memory is consolidated and your body releases hormones to regulate growth and appetite. Having a good night’s sleep leaves you refreshed and alert. If you sleep badly or not long enough, you will be less able to concentrate or make good decisions. You will also be more hungry, and have a bigger tendency to overeat. So what actually happens when you sleep?

Sleep Cycles

During your sleep, you go through a number of 90-120 minute cycles. In the first part of each cycle, often referred to as the “deep sleep” phase, your muscles are repaired and your body releases hormones to regulate growth and appetite. This phase is essential for maintaining a healthy body and takes up a larger proportion of your sleep early in the night.

In the second part of each cycle, the REM phase, you dream and your memory is consolidated. This phase is important when you are trying to learn complex tasks. The REM phases start short but get longer as the night progresses.

During a healthy sleeping cycle, people will wake up several times. Normally, these waking moments last for 1 or 2 minutes and are not remembered the next day. However, if you are under a lot of stress, you can wake up fully and have trouble getting back to sleep. If this happens, it will often take a full sleep cycle (90-120 minutes) to fall asleep again. Stress can be caused by your work or family life, but alcohol and caffeine also raise your body’s stress levels.

Slave to the Rhythm

Our sleep cycle is based on a circadian rhythm which reacts to the natural light/dark cycle of the day. When night approaches, the red light of dusk signals to your body that it is time to produce the sleep hormone melatonin. Then, the next morning, the cold blue light signals that it is time to decrease your melatonin and increase your cortisol levels again.

But we have disrupted these patterns by allowing blue light to become an integral part of our evenings. We stare at computer and phone screens right up to the moment we go to sleep (often when we are already in bed), making it impossible to fall asleep quickly. And because we get bored staring at the ceiling, we are continuously tempted to reach for our phone again. And so we lie awake, unable to fall asleep, staring at our Facebook feed.

To make matters worse, we spend our days at offices that get little outside light. Even a well lit office space has a light intensity that is 10-100 times dimmer than daylight. And so we sit in office twilight, fighting sleep and confusing our circadian rhythms even further.

Sleep Myths

The general lack of understanding of what happens when we sleep has given rise to many sleep myths that have gotten us from bad to worse. We’ll unpack a few of the more common myths for you here:

Myth #1 – You can catch up on sleep in the weekend
During hectic weeks, you may miss a few hours of sleep here and there. It is tempting to think you can just sleep in on Sunday and make everything right again. However, research shows that even if you wake up feeling less tired on Sunday, the effect lasts only a few hours. As the day goes by, symptoms of sleep deprivation come flooding back. It is important to make an effort to go to bed at a reasonable hour every day.

Myth #2 – Watching TV helps you fall asleep
Although the flickering light and constant background noise can override the thoughts that are keeping you up, always sleeping with the TV on can cause serious health problems including depression. TV also emits blue light, which messes with your circadian rhythm.

Myth #3 – Alcohol helps you sleep
Alcohol will certainly help you fall asleep, so it’s not hard to see where this myth came from. However, as alcohol is metabolized during the night, it will actually make it more likely for you to wake up in the middle of the night. And because your body has not yet fully metabolized the alcohol, those moments of wakefulness are rather more unpleasant than usual. In short, alcohol may help you fall asleep, but the quality of your sleep suffers. This is true even for small amounts of alcohol.

Sleep apnea

A common sleep disorder is obstructive sleep apnea, characterized by brief and repeated interruptions in your breathing while you sleep. It is caused by an inability of your throat muscles to keep your airway open. Because regular breathing is impaired, it causes fragmented sleep and low blood oxygen levels. During the day, this may lead to bad moods and memory problems. If left untreated, it can lead to hypertension and heart disease. It is made worse by alcohol and by being overweight, which can lead to a vicious cycle. Being overweight impacts the quality of your sleep, while inadequate sleep increases your appetite during the day, making it harder to lose weight.

If you are often snoring, sleep fitfully or regularly drift off during the day, you might be suffering from sleep apnea. We advise you to get checked because there are effective treatments, and sleeping well will greatly increase your chances to live a healthy life. Staying away from alcohol and cigarettes can reduce the severity of your apnea. Don’t take sleeping pills, as these will relax your throat muscles even more and aggravate the problem.

Improving your sleep

Although some nights will always be better than others, there are a lot of things you can do to optimize the quality of your sleep. We have dedicated a separate article to the things you can do to improve your sleep.