# Partner, travel & environment: what the research actually says

Your bed partner, hotel rooms and the first night anywhere new all change your sleep in measurable, testable ways.



## All studies

- **Bed-sharing in couples is associated with increased and stabilized REM sleep and sleep-stage synchronization** — Drews HJ, Wallot S, Brysch P, et al. (2020), Frontiers in Psychiatry 11:583. Counterpoint: in young couples, co-sleeping increased REM — the effect of a partner is individual; test it.

- **Two in a bed: the influence of couple sleeping and chronotypes on relationship and sleep. An overview** — Richter K, Adam S, Geiss L, Peter L, Niklewski G (2016), Chronobiology International 33(10):1464–1472. Objective sleep is often worse when sharing a bed, though subjective satisfaction can be higher — hence the 'partial sleep divorce'.

- **Night watch in one brain hemisphere during sleep associated with the first-night effect in humans** — Tamaki M, Bang JW, Watanabe T, Sasaki Y (2016), Current Biology 26(9):1190–1194. On the first night in a new place, one hemisphere sleeps lighter and is more responsive to sounds — the first-night effect is a vigilance mechanism.

- **Effect of inhaled lavender and sleep hygiene on self-reported sleep issues: a randomized controlled trial** — Lillehei AS, Halcón LL, Savik K, Reis R (2015), Journal of Alternative and Complementary Medicine 21(7):430–438. Lavender inhalation plus sleep hygiene improved sleep quality more than hygiene alone — a small, safe 'stackable win'.

- **It's more than sex: exploring the dyadic nature of sleep and implications for health** — Troxel WM (2010), Psychosomatic Medicine 72(6):578–586. Sleep is dyadic: partners' movements, schedules and conflict measurably shape each other's sleep.

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Educational summary of published research, not medical advice. Screening scores are not diagnoses. If a score is elevated or you feel unwell, talk to a clinician.

SleepShred for iPhone: https://apps.apple.com/app/id6802040541