▁ ▁Daily ▁variation ▁ ▁In tra oc ular ▁pressure ▁var ies ▁throughout ▁the ▁night ▁and ▁day . ▁The ▁di urn al ▁variation ▁for ▁normal ▁eyes ▁is ▁between ▁ 3 ▁and ▁ 6 ▁mm H g ▁and ▁the ▁variation ▁may ▁increase ▁in ▁gla u com at ous ▁eyes . ▁During ▁the ▁night , ▁int ra oc ular ▁pressure ▁may ▁not ▁decrease ▁ ▁despite ▁the ▁slower ▁production ▁of ▁a que ous ▁hum our . ▁ ▁In ▁the ▁general ▁population , ▁I OP ▁ranges ▁between ▁ 1 0 ▁and ▁ 2 1   mm ▁H g ▁with ▁a ▁mean ▁of ▁about ▁ 1 5 ▁or ▁ 1 6   mm ▁H g ▁( plus ▁or ▁minus ▁ 3 . 5   mm ▁H g ▁during ▁a ▁ 2 4 - hour ▁cycle ). ▁ ▁Gla u com a ▁patients ' ▁ 2 4 - hour ▁I OP ▁profiles ▁may ▁differ ▁from ▁those ▁of ▁health y ▁individuals . ▁ ▁F it ness ▁and ▁exercise ▁ ▁There ▁is ▁some ▁incon clus ive ▁research ▁that ▁indicates ▁that ▁exercise ▁could ▁possibly ▁affect ▁I OP ▁( some ▁posit ively ▁and ▁some ▁neg atively ). ▁ ▁Musical ▁instruments ▁ ▁Play ing ▁some ▁musical ▁wind ▁instruments ▁has ▁been ▁linked ▁to ▁increases ▁in ▁int ra oc ular ▁pressure . ▁ ▁A ▁ 2 0 1 1 ▁study ▁focused ▁on ▁br ass ▁and ▁wood wind ▁instruments ▁observed ▁" tem por ary ▁and ▁sometimes ▁dram atic ▁elev ations ▁and ▁fl uct u ations ▁in ▁I OP ". ▁Another ▁study ▁found ▁that ▁the ▁magnitude ▁of ▁increase ▁in