How caffeine, alcohol and exercise affect sleep

After a sleepless night, you are the worst version of yourself: you don't think well, you get distracted all the time and you get frustrated in public. It is enough to not get enough sleep for only 1, 5 hours for attentiveness to decrease by a third. But spending 7-8 hours in bed doesn't mean getting enough sleep. Disrupted sleep patterns, frequent awakenings, or snoring may make you feel overwhelmed even if you have had enough time.

These disorders are often blamed on caffeine, alcohol, and exercise shortly before bed. We found out what scientists think about it.

Can coffee really disrupt sleep?

As a rule, for a good rest, it is advised to exclude coffee in the afternoon. And this advice did not arise from scratch. In one experiment, [400 mg of caffeine (about four cups of coffee) decreased overall sleep duration, even though participants took it as much as 6 hours before going to bed. In another study, 200 mg of caffeine at 7 a.m. energized subjects so that even after 16 hours they slept less and worse than usual.

But not everything is so simple. The effect of caffeine on sleep depends on many factors, including:

Genetic prerequisites. Caffeine sensitivity is determined by different variations in the gene for adenosine receptors A2A. For a person with one modification, a mug of latte is enough to stay awake at midnight, a coffee lover with a different allele will yawn half an hour after a double espresso.
Features of the environment. A study in a remote village in Ecuador found coffee had no effect on sleep. Scientists have suggested that caffeine interferes with sleep only together with the secondary triggers of insomnia: light and noise at night. Indeed, bright light for 3 hours spoils sleep twice as much as a cup of invigorating drink.
Reaction to stress. Coffee is more of a problem for people whose sleep is highly stress-dependent. The more sensitive a person is, the more careful he should be with caffeine, especially during a stressful period of life.
The presence of bad habits. A recent study showed that coffee 4 hours before bed does not affect the quantity and quality at all, but cigarettes take about 40 minutes. Since coffee and cigarettes are often paired, nicotine may be the reason.

An analysis of over 2,000 randomly selected people showed that when gender, age, smoking, and seasonal fluctuations were taken into account, coffee consumption had no effect on sleep problems. And here are the conclusions that can be drawn from this.

If you are looking for the cause of sleep problems, first eliminate smoking and bright lights (including from gadgets) at least an hour before bed, and then analyze the effect of coffee.
If stress often makes you sleepy, try a caffeine-free diet. You may be more sensitive to its effects than other people.
If you have been drinking a lot of coffee for several years, including before going to bed, and then suddenly you have problems, look for the cause in something else.

Can exercise reduce sleep quality?

In general, exercise helps you fall asleep faster, sleep longer and get better sleep. Physical activity protects against insomnia: the more exercise, the less often it happens.

Any workout has a positive effect: aerobic, strength, frequent and rare, intense and not so. After being active, people of all ages sleep better: adolescents, adults, the elderly.

Moreover, elite athletes sleep better, recover more efficiently and wake up less often than ordinary people after exercising.

Training time doesn't really matter either. A review of 23 scientific papers on the topic showed that evening classes do not interfere with nighttime rest. On the contrary, after being active, people spend a little more time in deep restorative sleep than without exercise.

Medium-intensity workouts, even 30 minutes before bed, will not prevent you from getting a great night's sleep.

The only exception is high intensity exercise. Exhausting daily workouts at maximum speeds reduce the quality of sleep and the physical capabilities of the body. But only professional athletes or beginners who do not listen to their body at all can drive themselves into such a state.

If you are building up the intensity and are concerned about the quality of your sleep, follow these tips:
- Eat a high protein diet.
- Cut back on fat.
- Don't reduce calories.
- Add more turkey and pumpkin seeds, which are rich in tryptophan. This amino acid produces melatonin, a hormone responsible for a good night's sleep.
If you have just started exercising and are having trouble resting - be patient a little, the body will adapt. When I switched to CrossFit training, I was tormented without sleep for several nights after the unusual exertion. But one week was enough for adaptation.

Now my usual workout goes until 21:00 and ends with a high-intensity complex, after which I am too lazy to move. On such days, it falls asleep especially quickly. Sometimes you want to do it right on the way home.
1. Train how you want, when you want. This will only improve the quality of your sleep.
2. It can only get worse because of a state of overtraining or because of unusually intense loads in the evenings. The first requires rest, the second - the adaptation of the body.
3. If you are afraid to sleep during periods of high intensity, eat less fat, more protein, and tryptophan-rich foods.
  
  How alcohol affects sleep
  
  The impact of alcohol depends on how much you drink. One dose is approximately 340 ml of beer, 140 ml of wine or 40 ml of spirits. A moderate amount is recognized as one dose for women and two for men, a large amount - four for women and five for men.
  
  Alcohol can have a calming effect and make you fall asleep faster, but sleep quality drops rapidly for several reasons.
  - The phase of REM sleep is inhibited. It is also called the rapid eye movement phase, or REM phase. It allows us to dream, affects memory and cognitive abilities. The first time the REM phase begins 90 minutes after falling asleep, lasts 10 minutes and then alternates with a slow one during the night, becoming more and more prolonged towards the end. Average volumes of alcohol, starting with two or three doses (0.4–0.8 mg ethanol per 1 kg of body weight), postpone the onset of the REM phase and generally reduce its duration. This disorder can cause daytime sleepiness and decreased concentration, and negatively affect memory. As for smaller doses, their effect is not so pronounced, but still exists. Alcohol can change phases and disrupt the integrity of sleep, even if by the time you fall asleep there is practically no sleep left in the body.
  - The overall duration of rest decreases. It takes you longer to fall asleep, it lasts less, and becomes intermittent and restless in the second half of the night. Small doses of alcohol do not shorten sleep time and may even increase it, but quality still suffers.
  - The load on the heart increases. The alcohol in your blood makes your heart beat faster when you sleep, like when you are stressed. This increases the stress on the cardiovascular system, not giving it the proper rest. Moreover, it does not matter how old you are and how active you are - the effect persists in any case. Even small doses reduce the restorative ability of sleep by 9, 3%, and medium and large doses - by 24 and 39%, respectively.
  - Breathing is depressed during sleep. Alcohol relaxes the muscles of the upper respiratory tract and reduces their patency, increases the resistance of the nasopharynx. As a result, you do not have enough oxygen, and in the morning you are haunted by headaches and fatigue, concentration and attention are reduced.
  - The production of growth hormone decreases. It is an anabolic hormone that promotes protein synthesis and fat burning. Acceptance of 0.8 g of ethanol per 1 kg of body weight (two to five doses) reduces the level of growth hormone in blood plasma by 70–75%. Therefore, it is especially important for athletes and those who want to improve their physical fitness to give up alcohol before bed.
  - The insomnia continues. At first, falling asleep after a couple of glasses is easier, because moderate doses have a sedative effect. However, after a week, tolerance is developed, and the negative effect on sleep persists. You will have to drink more and more to fall asleep, and the quality of rest will decrease, causing headaches and fatigue.
  1. If you can not drink at all, do not drink.
  2. If you can't, drink no more than one or two drinks of alcohol, and preferably well before bed.
  3. Do not try to treat insomnia with alcohol. At first it will help, then tolerance will develop, and the quality of sleep will decrease.
    
    What is the bottom line
    
    Coffee may interfere with sleep if you are caffeine-sensitive, stressed, and in bright light (even from your gadgets) before bed. If any of this is about you, drink the last mug no later than 5 pm.
    
    Workout will only provide you with benefits, even if you exercise 30 minutes before bed. The exception is loads at extreme intensity, unusual or constant, leading to overtraining. If this is what you need to do, stick to a protein diet and eat foods rich in tryptophan to reduce the negative effects.
    
    Alcohol badly affects sleep in any amount, but moderate use (one or two doses per day) is less harmful. Eliminate alcohol altogether or try to keep it to a minimum.