wakefulness and performance, and recovers certain qualities of lost night sleep. .... However, midday napping is not a long-term solution for the maintenance of alertness ... Taking a brief nap after lunch (post-lunch nap) can be considerably effective in ... effects only happen if it is followed by stage 1 sleep (Hayashi et al.
Please cite as: Mohd Amzari Tumiran, Noor Naemah Abdul Rahman, Rohaida Mohd Saat, Nurul Kabir, Mohd Yakub Zulkifli, and Durriyyah Sharifah Hasan Adli (2015). The concept of qailulah (midday napping) from neuroscientific and Islamic perspectives. Journal of Religion and Health. doi: 10.1007/s10943-015-0093-7
The Concept of Qailulah (Midday Napping) from Neuroscientific and Islamic Perspectives Abstract: Napping/siesta during the day is a phenomenon which is widely practised in the world. However, the timing, frequency and duration may vary. The basis of napping is also diverse, but it is mainly done for improvement of alertness and general well-being. Neuroscience reveals that midday napping improves memory, enhances alertness, boosts wakefulness and performance, and recovers certain qualities of lost night sleep. Interestingly, Islam, the religion of the Muslims, advocates midday napping primarily because it was a practice preferred by Prophet Muhammad (pbuh). The objectives of this review are to investigate and compare identical key points on focused topic from both neuroscientific and Islamic perspectives, and make recommendations for future researches. Keywords: nap; sleep; neuroscience; Islamic perspective; religion; siesta Introduction The recommended duration of night sleep for adults, a necessary activity which is “naturally unavoidable”, is 8 hours per night; a duration which could avoid neurobehavioral declines (Van Dongen et al. 2003). Less than 6 hours of daily night sleep for four or more continuous nights may result in negative effects on cognitive and physiological functions (Belenky et al. 2003), and interfere with stable appetite (Spiegel et al. 2004), immune regulation (Maurovich-Horvat et al. 2008; Krueger et al. 2011; AlDabal and BaHammam 2011), and metabolic and endocrine functions (Maurovich-Horvat et al. 2008; AlDabal and BaHammam 2011). Sleep deprivation was found to lead to depression and anxiety in early childhood (El-Sheikh and Arsiwalla 2011). However, the regional average duration of night sleep varies; for example among the people of the United States it is slightly less than 7 hours (National Sleep Foundation 2009). Therefore, a “normal” population may benefit from napping (Harrison et al. 2011). There is also the case of those living in the hot desert and savannah climates who practice napping to help them get through the hottest part of the day, which seemingly has served human growth and survival (Monk 2005) and functions as an energy conservation (Barone 2000) mechanism. It is also a normal daily practise for the elderly people to take naps during the day. Napping is also an effective solution to daytime sleepiness for shift-workers (Oexman et al. 2002; Takahashi and Arito 2000), or people with sleep disorders (Takahashi 2003; Lai 2005). Qailulah is the word used in Islamic literature to describe midday napping/ siesta (BaHammam and Gozal 2012). Interestingly, Islam, the religion of the Muslims advocates midday siesta as a form of religious practice since it was preferred by Prophet Muhammad (pbuh). Emulating his practices, known as Sunnah, is highly recommended in Islamic principles and is a way to gain blessings and/or rewards from God. The concept of qailulah has certain specific features based on some Qur’anic verses and hadiths (the sayings and actions of Prophet Muhammad (pbuh)). Hence, the practice of napping, although common, varies across world-wide cultures. The objective of this review is to understand the midday napping practise from both neuroscientific and Islamic perspectives. In addition, this review will discuss similarities and differences between both perspectives, and reassess the existing related researches, and make suggestions for further studies.
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Neuroscience Perspective of Midday Napping Neuroscience advocates midday napping for the following cases: (a) response to sleep loss, i.e. replacement napping (Waterhouse et al. 2007; Faraut et al. 2011); (b) in preparation for sleep loss, i.e. prophylactic napping (Jackson and Moreton 2013); or (c) simply nap for relaxation, i.e. appetitive napping (Mednick 2013). Even for individuals who, generally, get good sleep on a nightly basis, napping still may lead to considerable benefits in terms of mood, alertness, and cognitive performance (Milner and Cote 2009). Besides, in healthy and rested subjects, midday napping enhances memory tasks performance (Mednick et al. 2002; Mednick et al. 2003; Tucker et al. 2006; Nishida and Walker 2007; Mednick et al. 2008; Cai et al. 2009; Wamsley et al. 2010a; Payne and Kensinger 2010). In general, benefits from napping are: (a) enhancement of alertness (Takahashi and Arito 2000; Brooks and Lack 2006); (b) better performance on vigilance (Kaida et al. 2012); (c) decrease in sleep latent period (Mignot et al. 2006); (d) improvement of reaction time (Brooks and Lack 2006; Ficca et al. 2010); (e) enhancement of driving task performance and alertness (Diez et al. 2011); (f) increased EEG activity on alertness (Tamaki et al. 2000; Kurdziel et al. 2013); and (g) memory improvement (American Academy of Sleep Medicine 2008). A recent theory, which has been put forward, is that napping has benefits in therapeutic healing and medical treatments, such as bringing down stress and blood pressure (Koroboki et al. 2012), and stimulating significant positive recovery in cardiovascular diseases (Naska et al. 2007; Zaregarizi et al. 2007; Brindle and Conklin 2012). Nap could function in managing sleep deprivation and arrhythmia (abnormal heartbeat) due to interfered circadian cycle (Verrier and Josephson 2009). The midday nap could function in recovering negative physical and psychological symptoms due to interfered night sleep (Bonnefond et al. 2001; Macchi et al. 2002) or narcolepsy (Takahashi 2003). It has been reported that 20%-40% of healthy adults are non-nappers (Pilcher et al. 2001). There is no clear explanation why they do not practise napping, but most probable reasons are (McDevitt et al. 2012): (a) not tired enough; (b) insufficient time; (c) waking up from napping is unpleasant or confusing. Other possible reasons are work ethics or cultural practices which prohibit napping during work. However, midday napping is not a long-term solution for the maintenance of alertness and vigilance performance due to night sleep loss. It is believed the lesser amount in diurnal napping naturally indicates that night sleep is not deprived. However, due to unpredictable and inevitable night sleep loss such as urgent situation or work purposes (e.g. nightshift works), midday napping is a temporary solution for stabilizing and maintaining the alertness and wakefulness performance. The effects of midday short nap, which improves alertness and performance during the midday/ afternoon, might be enhanced either by caffeine intake before the nap, or by bright light exposure or face washing instantly after the nap (Hayashi et al. 2003). The combination of bright light exposure and caffeine intake may scale down melatonin secretion (hormone associated with sleep) and increase alertness, body temperature and performance after having sleep deprivation in the previous night (Wright et al. 2000). There are even suggestions that short duration of bright light exposure after midday napping can help prevent sleep inertia (Phipps-Nelson et al. 2003), improve mood stability, alertness and performance (Kaida et al. 2007), and even beneficial for social interaction and job satisfaction at the workplace (Judge and Ilies 2004). However, there is no consensus on bright light effects since there is also a report that emotional stability and sleepiness are worsened with only the exposure to bright light (Burgess et al. 2002).
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Nap Timing and Duration Those who frequently nap throughout the day generally demonstrate increase sleepiness at around the practised time compared to those who are treating themselves with only a midday nap. A specific timing of napping seems to be of importance from two seemingly separate perspectives. Neuroscientific studies reported midday napping should occur between 2 pm to 4 pm, and not after 4 pm; or it will affect one’s ability to sleep at night (Samuels and Alexander 2013). Taking a brief nap after lunch (post-lunch nap) can be considerably effective in enhancing alertness and vigilance performance after a normal night’s sleep (Tietzel and Lack 2001). It also gives temporary memory and cognitive stabilization if there is sleep deficit during the previous night (Takahashi and Arito 2000). Various lengths of brief naps have been observed with different benefits priority, e.g. 20 minutes (Hayashi et al. 2003), 15 minutes (Oriyama et al. 2014) and 10 minutes (Brooks and Lack 2006), with shorter nap not necessarily indicating lesser benefits than a longer nap. Less than 30 minutes midday napping apparently has positive effects on daytime alertness (Hayashi et al. 2003). A midday short nap contains stage 2 sleep of 3 minutes duration, which is effective in restoring health and strength. However, these recuperative effects only happen if it is followed by stage 1 sleep (Hayashi et al. 2005). A short 20 minutes nap in the mid-afternoon has positive effects upon the maintenance of the daytime vigilance level (Hayashi et al. 2003) and can be very useful as a countermeasure to post-lunch sleepiness. It is more than enough to give recuperative effects, but short enough to steer clear of sleep inertia since it lacks slow wave sleep (SWS) (Kaida et al. 2003; Kaida et al. 2006; Milner et al. 2006). Hence, the negative effect on subsequent night sleep is expected to be slight. However, 10 minute nap is the most effective afternoon nap duration that has been examined so far (Brooks and Lack 2006), with its positive effects due to the beginning of delta-wave activity or the fixed accumulation of stage 2 sleep or total sleep. The Basic Physiology of Sleep Normal sleep for a typical healthy adult human consists of four stages with specific characteristics. It can be broadly divided to rapid eye movement (REM) and non-REM (NREM) sleep, each occurring recurrently several times throughout the night sleep with definitive characteristics (Kandel et al. 2013): (a) REM sleep has desynchronized electroencephalogram (EEG), muscle paralysis, dreaming and vivid eye movement; (b) NREM sleep contains variform EEG types, i.e. K-complexes, sleep spindles and SWS, associated with low-level muscle activity and lack of prominent eye movements. Sleep initiates with NREM and proceeds to subsequent NREM stages (stages 2, 3, and 4) before entering into REM sleep, which occurs in about 80 to 100 minutes after the first cycle of NREM. Both NREM and REM rotate in intervals of ~90 minutes period. NREM stages 3 and 4 occur frequently in the initial NREM cycles, and REM extends throughout the night (Carskadon and Dement 2011; Kandel et al. 2013). In general, changes in sleep cycle occur with age, for example newborn babies initiate their sleep with REM before NREM and have ~50 minutes for each sleep cycle. REM activity is detected in ~50% of the total sleep in the newborn and scales down over the first 2 years to ~20% to ~25% (Carskadon and Dement 2011).
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As for the old age, REM sleep patterns become similar to children, except in people with dementia. NREM of SWS is present only in the first 2 years. SWS declines across adolescence by ~40% from young adulthood and gradually declines during old age (Carskadon and Dement 2011). Benefits of Napping on Memory and Learning Process A series of recent studies (Mednick et al. 2003; Backhaus and Junghanns 2006; Tucker et al. 2006; Nishida and Walker 2007; Lahl et al. 2008; Tucker and Fishbein 2008) corroborate that performance on two types of long-term human memory, procedural and declarative memory, could be enhanced through an optimum midday nap. In adolescence especially, midday napping is helpful in reinforcing declarative memory (Tucker et al. 2006). However, the study by Backhaus and Junghanns (2006) found that procedural memory, but not declarative memory, of 34 young healthy subjects aged 18-25 years old can be reinforced significantly through napping (Backhaus and Junghanns 2006). Napping also seemed to be more beneficial throughout early life in consolidating procedural memory (Schabus et al. 2004; Rasch et al. 2007; Wilhelm et al. 2008; Backhaus et al. 2008; Prehn-Kristensen et al. 2009). Afternoon napping contains stage 2 and others of NREM sleep. Sleep researches using large animal model (Lee and Wilson 2002; Ji and Wilson 2007), showed that hippocampal neural networks due to spatial explorations were reactivated during NREM sleep and possibly lead to improvements of human spatial navigation ability during sleep. Furthermore, following a nap session, children recalled 10% more of the spatial locations than if they had been kept awake (Kurdziel et al. 2013). Thus, improved techniques should be applied to induce this critical midday napping in normal children. Napping has a role in consolidating memory after a learning session. Enhancement of memory process in humans can be clearly achieved by post-learning sleep (Diekelmann and Born 2010). There are studies (e.g. Peigneux et al. 2004; Wamsley et al. 2010a) suggesting that offline processing and consolidation of memory occurs during sleep, which lead to increased ability for keeping post-sleep memory intact. The memory loss after some perceptual learning session could be reversed by a 60-90 minutes nap, which contains both SWS and REM sleep (Mednick et al. 2003). The occurrence of REM sleep during nap can improve the memory performance after a learning process irrespective of the nap duration itself. Currently, there is no evidence that afternoon nap produces a significant decrease in the length of the subsequent night sleep or loss of the learning benefits from that night sleep (Allen 2003). In contrast to REM sleep benefits, post-learning NREM sleep from a brief napping shows some benefits for spatial memory performance (Wamsley et al. 2010b). Memory stabilizing and enhancement of wakefulness performance occurred only if the post-learning nap was rich in delta-wave activity (Wamsley et al. 2010b). Although a study by the American Academy of Sleep Medicine (2008) found that deficit in night sleep for 10 minutes could increase approximately 1.3% in REM percentage during napping, a nap without a previous sleep deficit usually lacks REM sleep compared to NREM, indicating the latter is sufficient to boost sleep-dependent performance benefits.
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Islamic Perspective of Midday Nap The word ‘sleep’ is mentioned more than 10 times in the Quran, reflecting that sleep activity is acknowledged in Islam to have a specific function in human life (Tumiran et al. 2010). Sleep phenomenon has made humans realize that they are not without their share of weaknesses, compared to God who is described to be the everliving, everlasting without the need to sleep or rest: “Allah! There is no God but He, the everliving, and everlasting. No slumber (sinah) can seize him nor sleep (naum)” (Qur’an 2:255). In the verse mentioned above both slumber (sinah) and sleep (naum) are distinctly mentioned with the word sinah closely matching the meaning of napping, either midday or otherwise (BaHammam and Gozal 2012). Napping in the day is acknowledged a few times in the Quran and considered as a part of natural human inclination designed by God. “And among His Signs is the sleep that you take by night and by day, and the quest that you (make for livelihood) out of His Bounty: verily in that are signs for those who hearken” (Qur’an 30:23). The Arabic word nu‘as is mentioned twice in the Quran. This word is the closest in describing midday napping, which is thought to be a better sleep quality compared to sinah. “Remember He covered you with a sort of drowsiness (nu‘as), to give you calm as from Himself” (Qur’an 8:11). “After (the Excitement) of the distress, He sent down calm on a band of you overcome with slumber (nu‘as)” (Qur’an 3:154). The verses explain how falling asleep for a short time provided a sense of calmness during a period of fear and stress. Muslim exegesis scholars (Ibn Kathir 2004; Al-Tabari 2009) interpreted the word nu‘as as an extreme drowsiness, which lead to deep sleep for a short duration and result in peacefulness and mind relaxation. During battle of Uhud and Badar, some of Muslim soldiers experienced this type of sleep (nu‘as), during which swords and shields in their hand were dropped unintentionally (Qur’an 8:11; 3:154). Qailulah (midday napping in Arabic) is encouraged in Islam based on hadiths (saying and action by Prophet Muhammad (pbuh)) which described the Prophet practising it. Emulating Prophet Muhammad (pbuh), including taking midday nap, is encouraged and rewarded in Islam. A few narrations by hadith scholars (Al-Bukhari, Muslim, Abu Daud, Ibn Majah and Al-Tirmidhi), on midday napping with roughly the same utterance are mentioned below (Table 1):
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Table 1: Midday napping/ siesta in prophetic traditions. The Translation
The Hadith References
Narrated Anas: “We used to offer the Friday prayer early and then have the afternoon nap.”
Sahih Al-Bukhari. The Book of Friday Prayer, volume 11, hadith 940.
Narrated Sahl bin Sa‘d: “We used to offer the Friday prayer with the Prophet (pbuh) and then take the afternoon nap.”
Sahih Al-Bukhari. The Book of Friday Prayer, volume 11, hadith 941.
Sahl bin Sa‘d said: “We did not have a midday nap or lunch till after the Friday prayer.” (Ibn Hajr added): “During the lifetime of the Messenger of Allah (pbuh).”
Sahih Muslim. The Book of Friday Prayer, volume 9, hadith 859.
Sahl bin Sa’d said: “We had a midday nap or lunch after the Friday prayer.”
Sunan Abu Daud. The Book of Prayer, hadith 1086.
It was narrated that Sahl bin Sa’d said: “We did not take a midday nap nor eat lunch until after Friday prayer.”
Sunan Ibn Majah. The Book of Establishing the Prayer and the Sunnah Regarding Them, volume 5, hadith 1099.
Sahl bin Sa‘d narrated: “We would not have lunch during the time of Allah’s Messenger (pbuh), nor would we have a midday nap, until after the Friday prayer.”
Sunan Al-Tirmidhi. The Chapter of Friday Prayer, volume 378, hadith 525.
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Islam accepts midday napping done before or after lunch, including after the Friday prayer as had been practised by the Prophet (pbuh). As described in the hadiths, midday napping should take place at specific times, before noon or early in the afternoon (Kan‘an 2000). Another practice which is highly encouraged in Islam is the waking up in the last third or other parts of the night to do worship activity, called qiamullail or tahajjud. Because this practice involves loss of some sleep, midday napping is crucial and indispensable in assisting one to perform daily activities during the day and even perform qiamullail in the next night. “They used to sleep but little by night [invoking their Lord (Allah) and praying, with fear and hope], and in the hours before dawn, they were (found) asking (Allah) for forgiveness” (Qur’an 51:17-18). Muslims are required to fast in the whole month of Ramadan (the 9th month of the Islamic calendar) and fasting is also encouraged on Mondays and Thursdays. Individuals who do fasting wil experienced sleep deprivation due to waking up to take a sahur (dawn meal) (Al-Ghazali 2001; BaHammam et al. 2013). Therefore, a Muslim would lose night sleep on a lot of days and this can be compensated by midday napping. However, there have also been studies (e.g. BaHammam 2004; BaHammam 2005) that found no change in daytime sleepiness among fasting performers as long as night sleep duration is still the same. Additionally, Prophet Muhammad (pbuh) prohibited meaningless activities (e.g. traduce or libelous) especially during Ramadan as it is a training period for good deed, conducts, and behavior so as to avoid sin. Thus, Muslims who might be concerned about misbehavior during fasting could practice the midday napping during Ramadan to avoid sins. Study among Muslims in UK and Libya (Waterhouse et al. 2008) indicates that midday napping is regularly practiced during the fasting month of Ramadan. This is put forward as positive evidence for the effect of midday napping in natural energy conservation and in reducing the physical, mental, and social activities during the holy month. However, the Prophet (pbuh) preferred being awakened from his midday nap for a more important activity, e.g. performing a prayer for the dead (funeral prayer): It was narrated from Yazid bin Thabit that they went out with the Messenger of Allah one day and he saw a new grave. He said: “What is this?” They said: “This is so-and-so, the freed slave woman of Banu so-and-so” - whom Messenger of Allah knew - “She died at midday and we did not like to wake you up when you were fasting and taking a nap." The Messenger of Allah stood (for prayer) and the people formed rows behind him. He said four Takbirs over her then he said: “If anyone among you dies while I am still among you, inform me, for my prayer for him is a mercy” (Al-Nasa’i). Islamic Practice of Sleep/Nap Positions Based on the practice of Prophet Muhammad (pbuh), two nap/sleep positions are preferred in Islamic practice: (a) lying on one’s right side; and (b) lying on the back side with one leg on another. Many times Prophet Muhammad (pbuh) would be on his right side, with his right palm placed under his cheek and this sleep posture is described in several hadiths: It was narrated by Hafsah: “When the Messenger of Allah would lie down, he would place his right hand under his right cheek, and he used to fast on Mondays and Thursdays” (Al-Nasa’i).
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It is expected that lying on the right side could improve the stability to a few bulky internal organs, which are physiologically placed more to the left part of the body. For instance, stomach, the major organ in the digestive process will not be physically stressed by other internal organs (e.g. liver, intestine, and pancreas) on the right side. Similarly, the heart, which is located on the left side, could pump blood throughout the body without physically stressed by other organs in the thoracic cavity. Others mentioned that such a position gives positive effect on sleep quality and emotion regulation (Agargun et al. 2004; Gordon et al. 2007). As for the other sleeping position assumed by the Prophet Muhammad (pbuh), is in the following hadith: ‘Abbad bin Tamim reported from his uncle that he saw Allah’s Messenger (pbuh) lying in the mosque (prayer site) and placing his one foot upon the other (Al-Bukhari; Muslim). In contrast, lying position with face downward was prohibited by the Prophet (pbuh), alerting that it is the position of sleep which is detested by God: Narrated Abu Hurairah that the Messenger of Allah (pbuh) saw a man lying on his stomach so he said: “Indeed such lying is not loved by Allah” (Al-Tirmidhi). Anatomically, such a position will cause physical stress to the internal organs in the thoracic and abdominal cavities. The Islamic Manners before Nap/ Sleep Either taking a nap or sleeping, Islam encouraged two actions in preparation for it. Prophet Muhammad (pbuh) encouraged Muslim to tidy up and/or clean the bed by shaking out or waggling the mattress or bed with a cloth while reciting a special doa/prayer before sleeping on it. Narrated Abu Hurairah: The Prophet (pbuh) said: “When anyone of you goes to bed, he should shake out his bed with the inside of his waist sheet, for he does not know what has come on to it after him, and then he should say: “In Your Name I have laid down on my side. If You take my soul, then have mercy on it. If You release it, then preserve it in the manner in which You preserve the men of right action” (Al-Bukhari). The former reduced the risk of breathing difficulties because such an act would remove the dust, dirt, mites, ticks or fleas on the bed (Doggett et al. 2012). Better inhaling acts would lead to improved oxygen supply through blood circulation to the brain during sleep. The nervous system, especially the brain, which normally receive 20% of total blood pumped by the heart will benefit from the act, in addition to the bed being clean/ safe from bugs, etc (Kandel et al. 2013). The latter action, put a person psychologically in a calm state of mind, having communicated with his/her Creator. Discussion and Conclusion From both perspectives of neuroscience and Islam, there are some similarities with regards to encouraging midday napping. From the Islamic perspective, although midday napping is not compulsory, Muslims are encouraged to do so to emulate Prophet Muhammad (pbuh), i.e. for wanting to gain blessings and good rewards from God. This is commonly referred to as doing a Sunnah (recommended religious practice) of the Prophet (pbuh). Various neuroscientific studies showed midday napping is beneficial in improving alertness 8
and vigilance performance, especially in the workplace. It also benefits memory consolidation (e.g. procedural and declarative memories) besides having a significant impact on spatial memory and creativity. The effects could consequently improve one’s cognitive level. Neuroscientific insight shows that people who require a midday nap are those who have night sleep deprivation, especially children (Franzen et al. 2009; Gujar et al. 2011). Autistic children with low quality of sleep could probably benefit from midday nap. Qailulah activity has been proven to be scientifically effective for generating the calmness and mental relaxation besides improving alertness and wakefulness performance level after sleep deprivation in the previous night (Lau et al. 2010). Midday napping has a prophylactic function in preparing conservation of energy (Jackson and Moreton 2013) to enable the qiamullail performance in the later part of the night (Al-Ghazali 2001). With reference to the significance of midday napping during fasting of a Muslim, scientific research indicates that it has a role in energy preparation which will be used during wakefulness (Kan‘an 2000). In terms of timing, a specific time of napping seems to be of importance from two seemingly separate perspectives. Islam encourages midday napping close to the beginning or after Zuhr/Jumaat prayer, i.e. about when the sun has moved slightly from mid-afternoon. This is in agreement with conventional science, which suggests that midday napping should not be done late in the afternoon, so as not to affect the night sleep. From neuroscience perspective, recent researches recommended that midday napping could be between 10 minutes to 20 minutes (Hayashi et al. 2003; Brooks and Lack 2006; Oriyama et al. 2014) to reap benefits from the nap. In conclusion, advocation of midday napping which is seen as a ritualistic activity in Islam, actually is supported by neuroscientific perspective. It significantly has positive effects on alertness, vigilance performance and memory enhancement. Islamic insights are also established for other related issues, like positions of the sleep, itself. Thus, midday napping should be widely practised to normal population and especially for those lacking quality sleep. Conflict of Interests All authors have nothing to disclose and have no commercial or financial interest in the products described in this paper. Acknowledgement The authors wish to thank the University of Malaya Research Grant (UMRG) RG272/14AFR for funding.
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