Why Men Sleep After Sex
Joyce Wagner
A coffee nap is just what it sounds like, coffee combined with a nap. It might seem counterintuitive to combine caffeine with sleep. But caffeine followed by a brief nap has been shown to improve alertness and mental acuity in several studies.
For coffee naps to work, both timing and sequence are important. Coffee naps are most beneficial when taken after lunch Trusted Source National Library of Medicine, Biotech InformationThe National Center for Biotechnology Information advances science and health by providing access to biomedical and genomic information.View Source , sometime during the mid-afternoon. Drinking coffee first, then napping for no more than 20 minutes, is key. Some research has shown that coffee naps may be better for helping people stay awake Trusted Source National Library of Medicine, Biotech InformationThe National Center for Biotechnology Information advances science and health by providing access to biomedical and genomic information.View Source than just drinking coffee or a nap alone.
Clearing of certain substances from the brain may enable deeper NREM sleep Trusted Source National Library of Medicine, Biotech InformationThe National Center for Biotechnology Information advances science and health by providing access to biomedical and genomic information.View Source . Studies show that good quality sleep Trusted Source National Heart, Lung, and Blood Institute (NHLBI)The NHLBI is the nation's leader in the prevention and treatment of heart, lung, blood and sleep disorders.View Source can positively affect decision making, problem solving, attention, and creativity.
Coffee naps have been shown to be effective in certain situations. For sleepy drivers and night shift workers, caffeine combined with a nap Trusted Source National Library of Medicine, Biotech InformationThe National Center for Biotechnology Information advances science and health by providing access to biomedical and genomic information.View Source can enhance cognitive and physical performance, problem solving, and mental acuity.
Several studies throughout the 1990s compared how well people performed after a caffeine nap versus taking caffeine or a nap alone. In one study, some participants were instructed to take 200 milligrams of caffeine and then take a nap before being kept awake for a period of 24 hours. Compared to participants who took only a nap, those who had a caffeine nap were better at maintaining alertness, logical reasoning, and performance tests.
Some researchers were particularly concerned with investigating whether caffeine and naps could improve alertness in drivers Trusted Source National Library of Medicine, Biotech InformationThe National Center for Biotechnology Information advances science and health by providing access to biomedical and genomic information.View Source , as sleepiness is a significant factor in many car crashes. One study found that those who took 150 milligrams of caffeine or a short nap were less drowsy Trusted Source National Library of Medicine, Biotech InformationThe National Center for Biotechnology Information advances science and health by providing access to biomedical and genomic information.View Source compared to drivers who took a placebo. Drivers who took a break to have caffeine or a nap significantly reduced sleepiness, driving impairments, and electroencephalographic (EEG) activity that indicates drowsiness.
More recent studies have investigated whether caffeine and naps can improve the physical performance of athletes Trusted Source National Library of Medicine, Biotech InformationThe National Center for Biotechnology Information advances science and health by providing access to biomedical and genomic information.View Source , particularly those who are sleep-deprived. Researchers compared the effects of either a 20 minute nap, a moderate amount of caffeine, or a dose of caffeine followed by a nap. Results showed that sleep-deprived athletes who combined caffeine with a nap performed better in sprinting tests than those who had either caffeine or a nap by itself.
Taking a coffee nap is fairly easy if you can find time to do so in your schedule. Basically, it requires quickly consuming caffeine and then immediately napping for between 15 to 30 minutes, preferably about 20 minutes. Coffee naps should be taken in the afternoon Trusted Source National Library of Medicine, Biotech InformationThe National Center for Biotechnology Information advances science and health by providing access to biomedical and genomic information.View Source , typically after lunch but not too close to bedtime.
Stress is assumed to impair sleep, but there is very little empirical evidence for this using sleep recordings. Here, we recorded sleep (at home) in 33 normal participants on three nights, which followed days with low, high and intermediate stress. The participants made daily ratings of the level of stress/worries at bedtime and also two-hourly ratings of stress. Only those 16 individuals who differed in stress/worries between two nights were analysed. There was a significantly lower sleep efficiency (81.0% versus 85.2%) a higher percent Wake (22.6% versus 15.6%) and a longer latency to Stage 3 (33.9 versus 18.3 min) during the nights with a higher stress/worry bedtime rating. None of the other sleep variables were affected. Also mean daytime stress ratings were significantly higher on the day preceding and following the high stress/worries sleep. It was concluded that moderate increases in stress/worries at bedtime are associated with moderately impaired sleep.
Sleep regulates immune functions. We asked whether sleep can influence immunological memory formation. Twenty-seven healthy men were vaccinated against hepatitis A three times, at weeks 0, 8, and 16 with conditions of sleep versus wakefulness in the following night. Sleep was recorded polysomnographically, and hormone levels were assessed throughout the night. Vaccination-induced Th cell and Ab responses were repeatedly monitored for 1 y. Compared with the wake condition, sleep after vaccination doubled the frequency of Ag-specific Th cells and increased the fraction of Th1 cytokine-producing cells in this population. Moreover, sleep markedly increased Ag-specific IgG1. The effects were followed up for 1 y and were associated with high sleep slow-wave activity during the postvaccination night as well as with accompanying levels of immunoregulatory hormones (i.e., increased growth hormone and prolactin but decreased cortisol release). Our findings provide novel evidence that sleep promotes human Th1 immune responses, implicating a critical role for slow-wave sleep in this process. The proinflammatory milieu induced during this sleep stage apparently acts as adjuvant that facilitates the transfer of antigenic information from APCs to Ag-specific Th cells. Like the nervous system, the immune system takes advantage of the offline conditions during sleep to foster adaptive immune responses resulting in improved immunological memory.
What happens to memories in your brain while you sleep? And how does lack of sleep affect your ability to learn and remember? NIH-funded scientists have been gathering clues about the complex relationship between sleep and memory. Their findings might eventually lead to new approaches to help students learn or help older people hold onto memories as they age.
While you snooze, your brain cycles through different phases of sleep, including light sleep, deep sleep, and rapid eye movement (REM) sleep, when dreaming often occurs. The cycles repeat about every 90 minutes.
Rohsenow et al. [14] examined powerplant performance in n = 61 merchant marine cadets the day following an evening of alcohol administration to achieve a BAC of 0.11%. Results were compared to an alcohol-free control test day. After an 8h period of supervised sleep, subjects reported significantly improved sleep quality in the alcohol condition. This unexpected finding may be explained by the fact that after alcohol consumption subjects reported significantly reduced sleep latency until sleep onset. Powerplant performance was not impaired in the hangover state.
Van Schrojenstein Lantman et al. [15] conducted a survey among 578 Dutch University students examining the impact of TST on the presence and severity of their past months latest alcohol hangover. Subjects who consumed more alcohol slept significantly longer. A positive correlation was found between TST and the duration of the alcohol hangover state. However, at the same time, prolonged TST was associated with significantly reduced overall hangover severity. Thus, reduced TST was associated with more severe hangover complaints. In a second survey by van Schrojenstein Lantman et al. [16], 335 adults reported that sleep quality was significantly worse after their latest alcohol consumption session that resulted in a hangover, and that daytime sleepiness was significantly increased compared to a regular alcohol-free day.
Earlier polysomnography studies with lower alcohol dosages revealed similar effects on sleep [9,20,21]. Alcohol significantly reduced sleep latency and the time spent in REM sleep. In the first half of the night, alcohol significantly increased the time spent in deep sleep (stage 3 and 4), while in the second half of the night, time spent in stage 1 sleep (drowsy light sleep) was significantly increased. The observations confirmed previous findings that after alcohol consumption people fall asleep quicker, spent less time in REM sleep in the first 4 h of sleeping [9]. The next 4 h, i.e., the second half of the night, sleep is more disturbed and fragmented, often characterized by multiple awakenings and increased time spent in Stage 1 sleep. Roehrs et al. [9] conducted a Multiple Sleep Latency Test (MSLT) the day following alcohol consumption (peak BAC 0.08%) or placebo. The assessments showed that throughout the post-alcohol day subjects were sleepier, as evidenced by the fact that they fell asleep significantly faster when compared to the alcohol-free day.
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