Peek At Science: 2023 February 14

Peak At Science 20230214
Quantum Biology

Peek At Science: 2023 February 14

Circadian phase resetting by a single short-duration light exposure

BACKGROUND. In humans, a single light exposure of 12 minutes and multiple-millisecond light exposures can shift the phase of the circadian pacemaker. We investigated the response of the human circadian pacemaker to a single 15-second or 2-minute light pulse administered during the biological night. METHODS. Twenty-six healthy individuals participated in a 9-day inpatient protocol that included assessment of dim light melatonin onset time (DLMO time) before and after exposure to a single 15-second (n = 8) or 2-minute (n = 12) pulse of bright light (9,500 lux; 4,100 K fluorescent) or control background dim light (<3 lux; n = 6). Phase shifts were calculated as the difference in clock time between the two phase estimates. RESULTS. Both 15-second and 2-minute exposures induced phase delay shifts [median (± SD)] of -34.8 ± 47.2 minutes and -45.4 ± 28.4 minutes, respectively, that were significantly (P = 0.04) greater than the control condition (advance shift: +22.3 ± 51.3 minutes) but were not significantly different from each other. Comparisons with historic data collected under the same conditions confirmed a nonlinear relationship between exposure duration and the magnitude of phase shift. CONCLUSIONS. Our results underscore the exquisite sensitivity of the human pacemaker to even short-duration single exposures to light. These findings may have real-world implications for circadian disruption induced by exposure to brief light stimuli at night.



背景 ヒトでは、12分間の単発の光照射と数ミリ秒の光照射により、概日リズムの位相がずれることがある。我々は、生物学的夜間に投与された15秒または2分の単一光パルスに対するヒトの概日リズムペースメーカーの反応を調査した。26人の健常者が9日間の入院プロトコルに参加し、15秒(n = 8)または2分(n = 12)の明るい光(9,500 lux; 4,100 K蛍光灯)または対照背景薄光(<3 lux; n = 6)への単一パルス暴露前後の薄光メラトニン開始時間(DLMO時間)を評価した。位相シフトは、2つの位相推定値間のクロック時間の差として計算された。結果 15秒および2分の露光は、それぞれ-34.8±47.2分および-45.4±28.4分の位相遅延シフト(中央値(±SD))を誘発し、対照条件(前進シフト:+22.3±51.3分)より有意(P = 0.04)だったが互いに有意差はなかった。同じ条件で収集された過去のデータとの比較により、曝露時間と位相シフトの大きさとの間に非線形的な関係があることが確認された。結論 我々の結果は、短時間の光への単一曝露であっても、ヒトのペースメーカーが絶妙な感度を持つことを強調するものであった。これらの知見は、夜間に短時間の光刺激に曝露することによって誘発される概日リズムの乱れに対して、現実的な意味を持つ可能性がある。

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