Love doesn’t just make your heart race, it can also make your eyelids heavy. Many people notice they feel unusually drowsy or relaxed around someone they deeply care about. Far from being laziness or a quirk, this effect has a solid basis in neuroscience, physiology and psychology.
When we are with someone we love, the brain releases oxytocin often called the “bonding hormone.” Oxytocin is associated with trust, intimacy and physical closeness. Importantly, it activates the parasympathetic nervous system—the part responsible for rest and digestion. This activation decreases stress hormones like cortisol and reduces heart rate and blood pressure, creating a state of calmness. Sleepiness is a natural extension of this relaxed physiological state.
From an evolutionary standpoint, humans are wired to remain alert when alone or in unfamiliar environments. Being in the presence of a trusted loved one signals safety, allowing the brain to “power down” its vigilance systems. Studies on attachment show that secure relationships decrease hypervigilance and anxiety which conserves energy and promotes rest. Love provides a psychological safety net that permits drowsiness without fear.
Cuddling, holding hands or lying close to a partner can trigger tactile stimulation of nerve endings that release endorphins. These physical cues not only increase feelings of comfort but also mimic pre-sleep relaxation processes. Functional MRI studies even show that social touch dampens activity in brain regions linked to stress and heightens activity in those associated with comfort and sleep readiness.
Couples often experience “sleep synchrony” where their sleep-wake cycles gradually align. Spending time with a loved one, especially in restful settings, can influence melatonin production and circadian rhythms, leading to drowsiness at similar times. Emotional closeness appears to regulate internal clocks, subtly aligning partners’ biological rhythms.
Perhaps the most telling explanation is psychological: drowsiness around a loved one reflects a deep level of trust. The body only allows itself to approach sleep when it feels safe. Feeling sleepy around someone is not a weakness but an unconscious testament to emotional security and intimacy.
References
Carter, C. S. (2014) ‘Oxytocin pathways and the evolution of human behavior’, Annual Review of Psychology, 65, pp. 17–39.
Feldman, R. (2017) ‘The neurobiology of human attachments’, Trends in Cognitive Sciences, 21(2), pp. 80–99.
Holt-Lunstad, J., Birmingham, W. and Light, K. C. (2008) ‘Influence of a “warm touch” support enhancement intervention among married couples on ambulatory blood pressure, oxytocin, alpha amylase and cortisol’, Psychosomatic Medicine, 70(9), pp. 976–985.
Heinrichs, M., von Dawans, B. and Domes, G. (2009) ‘Oxytocin, vasopressin and human social behavior’, Frontiers in Neuroendocrinology, 30(4), pp. 548–557.
Kent, R. G., Uchino, B. N., Cribbet, M. R., Bowen, K. and Smith, T. W. (2015) ‘Social relationships and sleep quality’, Annals of Behavioral Medicine, 49(6), pp. 912–917.
Mileva-Seitz, V. R., Bakermans-Kranenburg, M. J. and van IJzendoorn, M. H. (2016) ‘Genetic mechanisms of parenting and parent-child relationships’, Parenting: Science and Practice, 16(2), pp. 105–108.
Troxel, W. M., Robles, T. F., Hall, M. and Buysse, D. J. (2007) ‘Marital quality and the marital bed: Examining the covariation between relationship quality and sleep’, Sleep Medicine Reviews, 11(5), pp. 389–404.