病棟で勤務する看護師が交替勤務中に感じる眠気と眠気のピーク時刻の実態

Sleepiness and Its Peak Time during Shift Work among Nurses Working in Hospital Wards

要旨

　目的：病棟で2交替制勤務および3交替制勤務に就く看護師の勤務中の眠気とそのピーク時刻を明らかにする．

　方法：交替制勤務に従事する看護師54名（男14/女40，最頻年齢階級35〜44歳）に，4週間の勤務中の眠気とそのピーク時刻を日誌に記録してもらい，勤務帯毎に記述的に分析した．

　結果：2交替制では日勤320回，夜勤82回，3交替制では日勤237回，準夜勤111回，深夜勤120回のデータを得た．日勤帯では37〜54％，準夜勤帯では47％，夜勤帯では68〜76％の勤務で眠気の訴えがあった．眠気のピーク時刻は勤務開始からの経過時間に依存せず，生体リズム（時刻）に準じた深夜勤帯の3〜5時頃，日勤帯の14〜16時頃，準夜勤帯の22〜23時頃が眠気の発生しやすい時間帯であった．

　結論：眠気がピークに達する時刻は，勤務開始からの経過時間に影響されるのでなく，主に生体リズムに依存しているようであった．

　Purpose: The study aimed to examine the actual state of sleepiness and its peak time during shift work(2-shift- and 3-shift-system) among nurses working in hospital wards.

　Methods: The participants were 54 nurses(14 male and 40 female, mode age-class 35-44) working in shifts. They were instructed to record their sleepiness and its peak time during shifts in logbooks for four weeks. The obtained data were descriptively analyzed for each shift type.

　Results: Data for 320 day shifts and 82 night shifts for the 2-shift system, and 237 day shifts, 111 semi-night shifts, and 120 late night shifts for the 3-shift system were analyzed. Sleepiness was reported in 37-54% day shifts, 47% semi-night shifts, and 68-76% late night shifts. Further, peak time of sleepiness was not dependent on the time elapsed from the start of the shift. Time when sleepiness was more likely to occur was around 3:00-5:00 in late night shifts, 14:00-16:00 in day shifts, and 22:00-23:00 in semi-night shifts, which likely varied according to their biological rhythm.

　Conclusion: The peak time of sleepiness did not correlate with the elapsed time since the start of the shift, but seemed to depend on the individual's circadian rhythm.