What is sleep deprivation?
Sleep disorders are widespread in our latitudes. Because according to the DAK Health Report of 2017, around 34 million employed German residents sleep poorly. The analysis of 2.6 million insured persons by the IGES Institute in Berlin provided these results, whereby a sleep disorder is categorized several times in a more precise context (i.e. more than 80 different sleep disorders). The main distinction is between duration of the disorder (i.e. acute, subacute or chronic= i.e. longer than 3 months) and organic or non-organic sleep disorder:
- Insomnias: These include difficulty falling asleep, difficulty staying asleep, waking up early in the morning, and consistently non-restful sleep. In addition, fatigue, attention or memory problems, or headaches may occur. Insomnia is among the most common types of sleep disorders.
- Hypersomnias: Here, despite an undisturbed day-night rhythm, there is excessive tiredness during the day.
- Sleep-related breathing disorders: This includes various forms of sleep apnea. In this case, the patient's own breathing may stop for a short time, often unnoticed.
- Circadian sleep-wake rhythm disorders: In this case, the sleep rhythm is disturbed and can possibly lead to insomnia.
- Parasomnias: Characterized by episodic interruptions of sleep due to physical events such as sleepwalking, nocturnal moaning or unconscious bladder emptying during the sleep phase.
- Sleep-related movement disorders: Sleep interruption is produced by physical movement. - A well-known example of this is the so-called restless legs syndrome.
- Isolated symptoms, norm variations, unresolved problems: This category includes all sleep-related symptoms that cannot yet be clearly classified as "typical" or "pathological". These include, for example: Short sleepers (i.e., less than 5 hrs.) or snoring and talking during sleep.
- Other sleep disorders: This includes all sleep-related disorders which cannot be clearly classified into any other category.
Although medical science is widely concerned with sleep and sleep-related disorders, studies analyzing the effect of sleep restriction on blood pressure are mostly limited by shorter study duration, severe sleep restriction, and insufficient attention to psychological distress as a possible mediator.
Analyzing Restricted Sleep:
Published in 2020, in the scientific journal American Heart Journal, this study examined the exhibited hypothesis that chronic sleep restriction in women may potentially lead to increased cardio-metabolic risk. Researchers expected unhealthy lifestyle, obesity risk, blood pressure, and glucose intolerance to increase in relation to sleep deprivation - especially in pre-menopausal women.
The randomized, crossover (i.e., comparative crossover), outpatient sleep restriction study consisted of two phases, each 6 weeks in length, with an additional 6-week washout period between sections. Sleep duration in each phase was equal to the study participants' respective regular bedtime and wake time during the habitual sleep phase (GS phase) and 1.5 hours less during the sleep restriction phase (SB phase for short). During the GS phase, participants should follow the regular routine. During the SB phase, wake time should be kept constant - but bedtime should be pushed back.
A community-based cohort of 237 women with a mean age of 34 years was assembled alongside a randomized crossover intervention trial of 41 women with a mean age of 30 years to determine the consequences of sleep restriction on blood pressure. While the cohort group was analyzed for associations between sleep and psychosocial factors, the intervention group measured blood pressure weekly. Psychological factors were also analyzed at baseline and endpoint.
In the cohort group, higher perceived stress, stressful incidents, and lower resilience were associated with shorter sleep, poorer sleep quality, and greater insomnia symptoms. In the intervention group, blood pressure was higher after a sleep restriction period than after a habitual sleep period. Psychological stress, however, was not affected by total weekly sleep time and failed to show an effect on blood pressure during the sleep restriction phase. In addition, the study also measured a certain protein complex (NF-κB), which is an important factor in the development of inflammation. Here, the results showed that low sleep quality, insomnia and longer duration of falling asleep were associated with increased activation of this protein complex.
According to the study, the results suggest that sleep restriction or common but mostly neglected sleep disorders such as poor sleep quality and insomnia may be associated with increased blood pressure and vascular inflammation.
A secondary study analysis also explored that women who changed their daily bedtimes less frequently without changing sleep duration exhibited less adipose tissue compared to women who changed their bedtimes more frequently. Thus, according to the analysis, a consistent sleep schedule without changing sleep duration could potentially improve cardiometabolic health by reducing obesity and inflammation. In any case, the studies show new insights into the interaction of sleep and its effects on health in women, which is why a regular sleep pattern should not be neglected.