講演情報
[PO1-04]How the Darkness of the Night Sky Contributes to Physical and Psychological Healing
*Midori Tanaka1, Kenichi Otani2, Takahiko Horiuchi1 (1. Chiba University (Japan), 2. Konica Minolta Planetarium Co., Ltd. (Japan))
キーワード：
NIRS、Heart rate variability、Subjective evaluation
People have long found peace and wonder in gazing at the night sky. However, modern light pollution has drastically reduced the number of visible stars, and its psychological and physiological impacts remain unclear. To better understand the “healing” effects of darkness, this study examined how varying levels of night sky brightness in planetariums affect human relaxation. Planetariums provide an ideal environment to replicate starry skies that are now rarely seen in daily life.
Nine visual stimuli were used: six static starry-sky projections representing different light pollution levels and three video scenes from everyday contexts. Dark conditions simulated the night sky in space or under a new moon, while bright conditions represented urban or twilight skies. Five adult women (mean age 24.2 years), all with prior experience observing the night sky, participated. Each stimulus was presented on a dome screen while psychological and physiological responses were measured. Physiological indices included oxygenated hemoglobin (OxyHb) concentration in the prefrontal cortex (via NIRS) and heart rate variability (HRV) for autonomic activity. Psychological evaluation used an 11-point Likert scale for “healing.”
Results showed that darker sky stimuli significantly reduced right-prefrontal OxyHb, indicating greater relaxation, and received higher healing ratings than bright-sky stimuli. The strongest healing effect occurred under darkness equivalent to a new moon. Meanwhile, under extremely dark 0 lx conditions, temporary stress was reported, but as dark adaptation progressed over time, feelings of healing increased. These results represent initial findings indicating that environmental factors like night sky darkness can contribute to mental health, providing new guidelines for light pollution countermeasures and the environmental and program design of planetariums. Recreating a dark night sky holds potential to contribute to spatial designs that promote physical and mental healing and to the realization of well-being.
Nine visual stimuli were used: six static starry-sky projections representing different light pollution levels and three video scenes from everyday contexts. Dark conditions simulated the night sky in space or under a new moon, while bright conditions represented urban or twilight skies. Five adult women (mean age 24.2 years), all with prior experience observing the night sky, participated. Each stimulus was presented on a dome screen while psychological and physiological responses were measured. Physiological indices included oxygenated hemoglobin (OxyHb) concentration in the prefrontal cortex (via NIRS) and heart rate variability (HRV) for autonomic activity. Psychological evaluation used an 11-point Likert scale for “healing.”
Results showed that darker sky stimuli significantly reduced right-prefrontal OxyHb, indicating greater relaxation, and received higher healing ratings than bright-sky stimuli. The strongest healing effect occurred under darkness equivalent to a new moon. Meanwhile, under extremely dark 0 lx conditions, temporary stress was reported, but as dark adaptation progressed over time, feelings of healing increased. These results represent initial findings indicating that environmental factors like night sky darkness can contribute to mental health, providing new guidelines for light pollution countermeasures and the environmental and program design of planetariums. Recreating a dark night sky holds potential to contribute to spatial designs that promote physical and mental healing and to the realization of well-being.