What factors can affect the quality of sleep?

There are a number of internal and external factors that can affect the human circadian rhythm or sleep-wake cycle, in layman’s terms. These include light, noise, temperature, jet lag, shift work, medical problems and a number of chemicals, as well as caffeine and alcohol consumption.

Light

Light is one of the most important external factors that can influence sleep. It affects the specialized cells in our retina, which tell the brain whether it is day or night.

We are now exposed to much more light at night than ever before, which has definitely affected our sleep patterns. Exposure to light in the late afternoon tends to postpone the sleep phase and has led us to prefer later sleep times.

Exposure to light in the evening can have a number of unpredictable effects, but one for sure is that we find it hard to get back to sleep. Certain problems can arise when our exposure to light changes due to travel across time zones or work shifts.

Normally, our internal clock has a powerful effect on our ability to sleep at various times throughout the 24 hours, as well as on our sleep stages.

Medical conditions

A wide range of medical and psychological conditions can influence sleep quality. These conditions include chronic joint pain, neuropathic pain, tinnitus, gastroesophageal reflux disease, premenstrual syndrome, etc.

Pain limits the depth of sleep and causes the quality of sleep to deteriorate. Psychological disorders include stress, anxiety, depression, PTSD and borderline personality disorder.

Sufferers tend to have more difficulty falling asleep and, when they do, they sleep little. This is probably because we are prone to respond to dangerous or stressful situations by waking up. The stress we experience during the day can stimulate this arousal response and make it difficult to sleep.

Chemicals

Medications such as antihistamines, beta blockers, alpha blockers and antidepressants can disrupt sleep. Beta-blockers, which are used to treat high blood pressure and are prescribed for a number of cardiovascular diseases as well as migraines, often cause a decrease in the amount of slow-wave sleep, and are also associated with frequent daytime sleepiness.

Alpha blockers, which are prescribed, among other things, for prostate conditions, are associated with decreased REM sleep, the deepest and most restorative sleep. Antidepressants can disrupt sleep because they decrease the duration of REM sleep. SSRIs have been found to cause insomnia.

Waking hours

During the day, our internal clocks often counteract this sleep drive by generating a wake-up signal that keeps us awake. The longer we are awake, the stronger this impulse becomes.

The alert signal diminishes and the impulse to sleep comes to the fore. One of the reasons for this mechanism is a chemical called adenosine, which accumulates in the brain during wakefulness. As its levels increase, it begins to inhibit the brain cells that promote alertness, and makes us sleepy. Irregular release of this chemical causes poor quality sleep and sleep disorders.

Alcohol and caffeine

Alcohol can make us sleepy, but the quality of sleep under its influence is usually poor. Alcohol has an excitatory effect late at night, so that drink may have exactly the opposite effect than expected.

Alcohol also tends to exacerbate the symptoms of sleep apnea, which would further compromise the sleep of people with this breathing disorder. Caffeine is indispensable in the morning for some people, but its half-life is 6 hours, which means that if you drink a coffee at 3 pm, your body will have processed 50% of it by 9 pm.

Noise and temperature

As much as possible, your bedroom should be completely quiet. As for temperature, the ideal sleeping range varies so much that there is no set optimal sleeping temperature. Of course, extremes of temperature should be avoided. If it is too cold, it may be impossible to get a deep and truly relaxing sleep.