Many want to sleep better, but it’s not always clear what actually affects sleep. When nights don’t go well, thoughts can feel slower, patience shorter, and the body less recovered.
Sleep isn’t just about feeling refreshed the next day. During the night, some of the body’s most important repair processes take place. The brain clears away waste products, the immune system works, and hormones that control hunger, stress, and recovery are balanced.
When sleep works as it should, the body gets a chance to restore itself. When it’s disturbed, even a little, it can affect energy, focus, and well-being.
What happens in the body when we sleep?
Sleep consists of several different phases that repeat in cycles throughout the night.
One of the most important phases is deep sleep. This is when the body focuses on physical recovery. Muscles repair, tissues rebuild, and the immune system activates.
Another phase is REM sleep, which is more connected to the brain. During this phase, the brain processes memories, emotions, and impressions from the day.
If any of these phases are disturbed, we can wake up feeling tired even after a long sleep.
The circadian rhythm controls when the body wants to sleep
Sleep is largely controlled by the body’s circadian rhythm, also called the biological clock. It tells the body when it’s time to be awake and when it’s time to sleep.
This rhythm has developed over millions of years. Long before electricity, screens, and late nights, people lived more in tune with the sunlight.
Even though our lives look different today, the brain basically still works the same way.
The circadian rhythm is controlled in part by the hormone melatonin, which starts to be produced when the light decreases in the evening. It’s the body’s signal that it’s time to switch to night mode.
This also means that how we live during the day affects how we sleep at night.
Day and evening habits that affect your sleep
If you want to sleep better naturally, the work actually starts long before you go to bed. How you live during the day affects how easily your body can wind down in the evening.
Get daylight in the morning
Getting daylight early in the day helps your body set its biological clock. When your eyes receive morning light, signals are sent to the brain that help your body understand when the day begins and when evening will come later.
Move your body during the day
Physical activity can contribute to deeper sleep later in the night. It doesn't have to be intense exercise. A walk or some movement during the day can go a long way.
Avoid late meals
Digestion is an active process. When the body is working to break down food, it is still in a more awake state.
Late meals can also affect blood sugar, which in turn can disrupt the body's nightly rhythms. If blood sugar fluctuates during the night, it can cause us to wake more easily or have lighter sleep.
Allowing the last meal to settle for a while before bedtime can help the body enter rest mode.
Dim the lights in the evening
Bright light in the evening can slow the body's production of melatonin, the hormone that signals that it is night.
Especially blue light from phones, tablets, and computers affects the brain's signals about when it's time to sleep.
Dimming the lights at home, putting away screens a while before bedtime, or using blue light blocking glasses can help the body understand that the day is coming to an end.
Keep roughly the same sleep schedule
The body likes regularity. Going to bed at about the same time every night makes it easier for the body to find its natural rhythm.
Sometimes it can also be about the body having difficulty winding down in the evening. For some, this shows up as restless legs when trying to sleep. Here you can read more about why it happens and what can help.
Glycine and sleep – what does the research say?
Besides habits and circadian rhythm, researchers have also looked at how certain nutrients can affect sleep.
One of them is glycine.
Glycine is an amino acid that the body uses in many different functions. It is, among other things, an important building block in collagen and also participates in the body's detoxification processes.
But glycine also acts as a neurotransmitter in the nervous system, where it can have a calming effect.
Several studies have examined the connection between glycine and sleep.
In a study published in Sleep and Biological Rhythms participants took glycine before bedtime. The results showed improved perceived sleep quality and less fatigue the next day.
Researchers believe that one of the mechanisms may be that glycine helps the body lower its core temperature slightly, which is a natural part of the falling asleep process.
In another study published in Frontiers in Neurology researchers saw that glycine could improve subjective sleep quality in people who experienced poor sleep.
That doesn’t mean glycine replaces good sleep habits. But together with a stable circadian rhythm and good evening routines, it can be a way to give the body better conditions for restorative sleep.
Melatonin and glycine – two different roles in sleep
Melatonin is often mentioned in connection with sleep. It is a hormone that the body starts producing itself when the light decreases in the evening. Melatonin mainly functions as a signal to the body that it’s time to sleep and helps regulate the circadian rhythm.
Melatonin supplements are sometimes used when the circadian rhythm has been disrupted, for example with jet lag or shift work. The effect is mainly about timing, that is, helping the body understand when it is night.
Glycine works differently. Instead of regulating the circadian rhythm, it seems to affect the body's physiology during the actual falling asleep process, partly through its role in the nervous system and by contributing to a slight lowering of the body's temperature.
Therefore, the two substances can be described as support on different levels: melatonin signals when it’s time to sleep, while glycine can contribute to the processes in the body that make it easier to wind down.
Good sleep is about more than just one thing
When sleep doesn’t work, we often look for a single solution. But research shows that sleep is almost always affected by several factors at the same time.
Light, stress, movement, eating habits, and circadian rhythm all interact in how the body regulates sleep.
When these parts work together, the body gets the best conditions to do what it is designed for: to recover during the night.
References
Bannai, M. et al. (2012). The effects of glycine on subjective daytime performance in partially sleep-restricted healthy volunteers. Frontiers in Neurology.
Chellappa, S. L. et al. (2013). Evening exposure to blue-enriched light impacts circadian physiology and cognitive performance. Journal of Applied Physiology.
St-Onge, M. P. et al. (2016). Meal timing and frequency: implications for metabolic health and sleep. Circulation.
Wright, K. P. et al. (2013). Entrainment of the human circadian clock to the natural light-dark cycle. Current Biology.
