Effects of periodic leg movements during sleep in middle-aged subjects without sleep complaints

Recent reports have called into question the relevance of periodic leg movements during sleep disorder (PLMSD) as a specific clinical entity. Because periodic leg movement in sleep index (PLMSI) increases with age, it has become an important exclusion criterion in research on aging. However, it is unknown if PLMSI is related to sleep quality in middle-aged subjects without sleep complaints. The sleep of 70 healthy, middle-aged subjects (age 40 to 60 years) without sleep complaints was evaluated. Subjects were divided into two groups according to their PLMSI severity: (1) 43 subjects (28 women, 15 men) were in the low PLMSI group (<5) and (2) 22 subjects (9 women, 13 men) were in the high PLMSI group (>10). A significantly higher proportion of men than women showed PLMSI greater than 5. There was no significant effect of PLMSI severity group for polysomnographic sleep parameters. PLMSI exerted a small but significant effect on subjective sleep quality, especially in middle-aged men. These results raise questions about the relevance of PLMSI as a pathological index for middle-aged subjects without sleep complaints and support the notion that an increase in PLMSI may be part of the normal process of aging associated with the loss of dopaminergic function.